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I
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THE
STRUCTURE and PHYSIOLOGY
O- F
c
. J
MAN
AND
O M P A R E D
WITH THOSE OF
! '
AND OTHER A N I M A L S.
ILLUSTRATED w th FIGURES.
Bv ALEXANDER MONRO, M. D<
FELLOW OF THE ROYAL COLLEGE OF PHYSICIANS,
t 1 I
AND OF THE ROYAL SOCIETY,
' ' i ' V
AND
PROFESSOR OF PHYSIC, ANATOMY, AND SURGERY, IN THE UNIVERSITY
O F
EDINBURGH.
EDINBURGH:
Printed for CHARLES ELLIOT, Edinburgh; And G. G. J. and J. ROBINSON, London.
M,DCC,LXXXV.
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TO THE RIGHT HONOURABLE
JAMES HUNTER-BLAIR of Dunskey, Esq^
^ \ • ' ' ,
- ' * * .. • r
LORD PROVOST OF THE CITY OF EDINBURGH;
THIS WORK IS INSCRIBED,
. *• w \
AS A MARK OF THAT RESPECT
\
THE AUTHOR THINKS DUE TO HIM,
ON ACCOUNT OF THE
» V. - •
LIBERAL AND IMPARTIAL SPIRIT
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« ' . ''' •••■ : '
WITH WHICH HE HAS PLANNED,
AND IS NOW EXECUTING,
' • ' ' t . /
VARIOUS SCHEMES,
. _ - i
NOT L-ESS USEFUL THAN ORNAMENTAL
%
' T O T H E
CAPITAL OF HIS COUNTRY.
\
The CONTENTS.
INTRODUCTION,
ff*
Page.
*3
CHAPTER I.
/ * \ • - r r
-A Defcription of the Heart, V ffels, and Circulation of the Blood in Fijhes i
C H A P. II.
14
Obfervations on the Circulation of the Blood in Fijhes,
CHAP. III.
18
Of the Glandular Organs ancl Secreted Liquors In Fijhes , - % j
Sect. I. Of Liquors fecreted on the External Surface of Fijhes , * ib.
Sect. II. Of Liquors fecreted into the Cavities of the Cranium , Pericardium, and
Abdomen , - - . ** - 22
* • * » 1 ,
Sect. III. Of Liquors fecreted into the Organs of Digefion, - 24
Sect. IV. Of the Secretions of the Male Organs , - - 25
Sect. V. 0/" Secretion in the Female Organs , and of the Nutrition f the Foetus, 27 Sect. VI. Of the Swimming-bladder of Fijhes, * <* Jb»
CHAP. IV.
' r f * * ^
. , > ^ ( , r *
, ,v . - • ft
^ Defcription of the Syfem of Abforbent Lymphatic Feffels in Fijhes, 2 9
Sect. I. ^ Defcription of the Syfem of Abforbent Lymphatic Fejfels in the Car¬ tilaginous Fifes, or Nantes Pinnati of Linnceus, ' ib.
_ f %
Sect. II. A Defcription of the Syfem of Abforbent Lymphatic Feffels in the Of feous Fijhes, or Pifces of Limueus, -* - - I
’ , . ’ i ■ *v
CHAP. V.
/ ^
■ * • • •' * i
Experiments and Obfervations on the Syfem of Abforbent Lymphatic Fejfels of Fijhes, - - - - * ^ 2
* , v - .y. ^ • * . ■ r '
CHAP. VI.
, | f
• , « ’ , 1
Obfervations on the Lymphatics of the Spleen in Fijhes , and on the Ufes in gene - ral of that Organ , - - - . f.
B
CHAP.
I
• .
'•
CONTENTS.
Page.
CHAP. VII.
Of the firf Eifcovery of the Syjlem of Abforbent LaBeal and Ly mphatic Vejfels In Birds , Fifes , and Amphibious Animals , - - 3^
CHAP. VIII.
Of the Brain and Organs of the Senfes in Fifes,
Sect. I. Of the Brain in Fifes, and Nervous Syfem in general. Sect. II. Of the Nofe in Fijhes,
43
ib.
44
Of the Ear in Fishes.
Sect. III. Of the Ear in the Cetaceous Fifes , * • 45
Sect. IV. Of the Ear of Amphibious Animals, and particularly of the Sea Tor- toife or Turtle , - 46
Sect. V. Of the Ear in the Cartilaginous and OJfeous Fifes , - 47
Sect. VI. A Eefcription of the Ear of a Skate , - - 48
Sect. VII. A Eefcription of the Ear of the Squalus Squatina, or Angel Fif , 50
Sect. VIII. A Eefcription of the Ear in fome of the long f aped Cartilaginous Fifes, and in the OJfeous Fifes, ib.
CHAP. IX.
Experiments on Hearing in JVater ,
CHAP. X.
Ofthefeveral W zys in which the Tremor of Sonorous Bodies is communicated,
in the different Clajfels of Animals, to the Nerves fpread out on the Bottom of the Ear, - • -
’ ‘ . 54
CHAP. XI.
Of the Eyes in Fifes ,
57
CHAP. XII.
The Anatomy of the Cuttle Fif, or Sepia Loligo,
62
CHAP. XIII.
V .
The Anatomy of the Sea Egg, or Echinus Marinus,
- 66
EXPLA-
l
'l
EXPLANATION of the TABLES.
TABLE I.
X -
Page*
The Figures of this Table reprefent the extent of the furface of the gills, the heart, the branchial arteries and veins^ and aorta of a Skate, filled with injedion, - - - % 4 "73
TABLE II.
r -• - , 0
In this Table the thoracic and abdominal vifcera, with the circulating veins of a female Skate, are reprefented, - - 76
TABLE III.
This Table fhows fully the arteries and circulating veins of the chylopoietic vifcera of a Skate, with a flight fketch of the ladeals, all filled with in¬ jection, - - 78
TABLE IIP.
This Table reprefents the mufcular coat of the mefenteric vein of an Ox, 79
TABLE IV.
In this .Table the lungs, the heart, and large veffels of a Sea Tortoife or Turtle are delineated, - - - ib.
. v r 1 ' ■ *
TABLE V.
This Table reprefents a large lymphatic vefTel fituated ori the fide of the Cod Fifh ; and likewife the principal duds which pour out mucus on the fur- face of the body, - - 80
TABLE VI.
1 * 1
This Table reprefents chiefly the mucous duds on the fore ' part of a Skate, 81
TABLE VII.
The Figures in this Table reprefent the duds which pour out mucus on the back part of the Skate ; and likewife the meatus auditorii externi, ib.
TABLE VIII.
This Table fhows two fmall canals at the fides of the anus in the Sturgeon, which lead into the cavity of the abdomen ; and tw;o other paffages, by which the cavity of the abdomen communicates, in that fifh, with the pelves of the kidneys, - - -83
TABLE
(
8
EXPLANATION of the TABLES.
TABLE IX.
/
Tins Table reprefents principal parts of the Uni dure of the abdominal vif- cera In a fmall female Skate,
* j
TABLE IX*.
Pag*.
%
This Table fhows the ftrudure of the pancreas and of the villous coat of the Inte (lines in the Sturgeon, - C 84
/ ’ -TABLE X.
Reprefentss the biliary duds of a Cod, with the termination of the Intefti- nula caeca, * * - 85
TABLE X*
\ '
V l' ~r V «• . ■
Reprefents the liver, gall-bladder, and biliary duds of the Wolf or Cat " EHh, - - . - * ib.
TABLE XL
This Table fliows the organs of generation and of urine in the male Skate, 86
» • . ^ 1
TABLE XII.
This Table reprefents the organs of urine and part of the organs of genera¬ tion in the male Skate, - „ - ib.
> ’ * ^
table XIII.
In this Table are reprefented the termination of the uteri and vefica urinaria of a Skate, in the common cloaca, ■ .
TABLE XIV.
r « .
In this Table, which reprefents the foetus of a Skate cut open, the dud is Ihown which conneds the yolk of the egg to the inteftinal tube, ' ib.
1 - ; * v
TABLE XIV*.
Reprefents a young fcetus of a Skate, with its blood-veflels, before the gills are covered, - . _ gg
* 1
TABLE XV.
This Table reprefents, in the Salmon, the Carp, and the Herring, a dud, by which the fwimming-bladder communicates with the oefophagus or fto* mach ; and a vafcular fubftance in the air-bag of a Cod, . j.
table XV*.
This Table reprefents the heart, ftomach, air-bag, and air-dud, of the Conger or Sea-Eel, -
89
table
N
EXPLANATION of the TABLES.
TABLE XVI.
Page.
This T able reprefents a large communication of the fwimming-bladder of the Sturgeon with his ftomach, - . - no
TABLE XVII.
This Table leprefents the abdomen laid open in a female Frog, g j
table XVIII.
In this Table the abdominal vircera of a Skate, with the lacteal and lym¬ phatic veflels filled with wax, and their termination on the right fide of the body, are reprefented, - . - n«
y 2
table XIX.
In this Table the heart and abdominal vifeera of a Skate, and the lacteal
and lymphatic veflels filled with wax, with their termination oil the left fide, are reprefented, - * ,
TABLE XXi
This table reprefents a vafcular and cellular receptacle of the chyle fituated
on the ftomach of a Skate, - ^ =.
yj
table xxi.
This Table reprefents the lymphatic veflels of the brain, the ear, the eye, and Ikin of a Skate injected with wax, - - 96
TABLE XXII.
# t
This Table reprefents the heart and abdominal vifeera of a Cod fifh, with the lacteals, receptacle of the chyle, and receptacle of the chyle and lymph, injected with wax, , . .
table XXIII.
I ' \
In this Table, portions of the lacteals of a Cod injected with wax are repre¬ fented of their natural fize, and alfo when viewed with a magnifying
■ • 99
TABLE XXIV.
This Table fhows the joining of the ladteal with the lymphatic veflels in the Cod,
IOO
TABLE XXV.
In this Table the receptacle of the chyle and lymph in a Haddock is repre- fented,
' ~ 101
table
(
10
E
XPLANATION of the TABLES.
Page.
TABLE XXVI.
In this Table the heart, branchial artery, venae cavae, and terminations of the lymphatic fyftem in a Salmon, are reprefented,
102
TABLE XXVII.
Reprefents the joining, together of the principal lymphatic veffels and the terminations of the lymphatic fyftem in a Salmon* - 103
TABLE XXVIII.
This Table {hows chiefly the terminations of the lymphatic fyftem and the hepato-cyftic duds of a Salmon, * - 104
TABLE XXIX,
This Table reprefents chiefly, in a fmall Salmon, the receptacle of the chyle and terminations of the ladeal and lymphatic fyftem, - ib.
TABLE XXX.
Reprefents the ladleals of a Sea Tortoife or Turtle,
TABLE XXXI. XXXII. and XXXIII.
io5
Reprefent, chiefly, certain fpheroidal bodies connected with the brain, fpi- nal marrow, and nerves of the Cod and Haddock, - 106, 107, 108
TABLE XXXIV.
This Table reprefents the upper furface of the brain and top of the fpinal marrow of a Skate, with the nerves ifluing from thefe, - 108
TABLE XXXV.
109
This Table reprefents the nofe, ear, and larynx of a Porpefs.
TABLE XXXVI.
Tl*is Table reprefents the organ of hearing of the Sea Tortoife or Turtle, 1 12
TABLE XXXVII.
This Table reprefents the bale of the brain of a Skate, and the feveral parts of the organ of hearing, * . . _
J
table XXXVIII.
This Table reprefents the upper or back part of the head and the ftrudure of the ear in the Squalus Squatina or Angel Fifh, ' . . 1
TABLE XXXIX.
In this Table the optic nerves and the feveral parts of the organ of hearing in the Cod are reprefented,
”7
TABLE
§
EXPLANATION of the TABLES.
1 1
-
v
Page,
T A B L E XL.
. * • ' • A f - «*.•
In this Table the nofe and ear of a Sturgeon are delineated, - i
TABLE XL*.
Reprefents a faction of the cryftalline lenfas of the Cod and the Ox, with other circumftances relating to the cryftalline lens, - 120
TABLE XLI. and XLII.
In thefa Tables the ftru&ure of the Cuttle Fiih or Sepia Loligo is reprc- fanted, - - . 1 2i, 123
TABLE XLIII. and XLIV.
Reprefent the parts, and particularly the abforbent veflels, of the Sea Egg or Echinus Marinus, - - . 124,125,
/ \
The
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/
• . • -- I- K “ 'r»l ' ,
t ... . ' ; * ’ , > .fi
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The Linnean Names of the Fishes and other Animals defcribed in this Woirk*
See Car oli a Linne Syftema Nature, edttio 13.
\
■ \ ' . . * ’ f / • r . , ' : _ . . ' ,
The Porpess. Lin. G. 40. Delphinus : Sp. I. Phocana .
The Turtle. G. i 19. Tejludo : Sp. 3. Mydas.
The Frog. G. 120. Rana: Sp. 14. Temporaria.
The Skate. G. 130. Raja: Sp. 2. Batis : Sp. 5. Fullonica .
The Angel or Monk Fish. G. 131. Squalus: Sp. 4. Squatina.
The Sturgeon. G. 134. Acipenfer : Sp. 1. Sturio,
Conger Eel or Sea Eel. G. 143. Murana : Sp. 6. Conger .
Sea Wolf or Sea Cat. G. 146. Anarhichas : Sp. 1. Lupus .
The Cod. G. 154. Gadus : Sp.3. Morhua .
The Haddock. G. i^.Gadus: Sp. 1. JEglejinus .
The Mackrel. G. 170. Scomber : Sp. 3. Tbynnus .
The Salmon. G. 178. Salmo: Sp. 1. Salar.
The Herring. G, 188. Clupea : Sp. 1 . Harengus.
The Carp. G. 189. Cyprinus: Sp. 1 ,Carpio: Sp.4. Trine a.
The Cuttle Fish or Sepia. G. 296. Sepia: Sp. 4. Loligo .
The Sea Egg or Echinus Marinus, G. 299. Echinus: Sp, i. E/culentus .
/
1
T H E
STRUCTURE and PHYSIOLOGY
O F
F
I
S
H
E
S
E X
LAI N E D,
AND
COMPARED with those of MAN,
INTRODUCTION.
I
Variety of curious circumftances' lias occurred to me in examining the ftrurhire of fifl.es, fome of which have been entirely overlooked, and others imperfectly deferibed by authors. As they relate to points of chief importance in the animal oeconomy , I flatter myfelf that an account of them
will be not lefs acceptable to the Phyfician than to the Naturalift.
By the generic term of Fi flies, I underftand that clafs of animals which lives in water, fwims by the afliftance of fins, and has the water diredly applied to the gills, through which organ the whole mafs of blood in the body paffes in the courfe of circulation.
This definition comprehends the Nantes Pinnati , as well as the Ptfces of Linnaeus; fince it will afterwards appear that thefe ought not to be farther feparated than
as different orders of one clafs of animals.
The Raja fhall be my chief example of the Nantes Pinnati , and the Gadus of
the Ptfces of Linnaus : but I fhall occafionally endeavour to throw farther light on the fubjed, by deferibing parts* of other fifhes ; and, to be better underftood, I fhall illuftrate my deferiptions with Figures reprefenting the paits of their natu¬ ral fize.
I fhall begin with tracing the blood from their heart, and its return to that organ.
I fhall next make fome curfory obfervations on their oigans of fecietion.
I fhall afterward give an account of their abforbent fyftem ; and
D
Shall
I
14 0» m HEART, VESSELS, and
' ( 1
Shall conclude with fome obfervations on their Brain, Nerves, and the Organs of their Senfes ( a ).
CHAPTER I.
- ■ ■ , 1 *
A Defcription of the Heart, Vessels, and Circulation of
the Blood, in Fishes.
IN all the fifhes I have difle&ed there is but one heart, confifting of one auricle and one ventricle ; and, from the latter, one artery is fent out, which is en¬ tirely fpent on the gills. From the gills, therefore, the returning blood pafles to
all the other parts of the body, without the intervention of a fecond heart, as in > man ( b ).
1 r * *
So far is generally known: but the whole courfe of the blood has not been traced
with fufficient accuracy ; fo that feveral curious and interefting circumftances have efcaped notice.
I fhall therefore give a particular defcription of the circulating veffels of the
Ikate, with which I have found the Pijces of Linnaeus agree in every material cir-
cumftance ; and I fhall begin with the branchial artery.
> v - ” . . ’ , / \
^ k \ . 1 \ 1 . . ' # 1
4 * 1
\ • N , /
SECT. I.
At the beginning of the branchial artery there are three femilunar valves (A the middle parts of which, analogous to the Corpufcula Morgagni, are much thicker than in man, and illuftrate the ufe of thefe organs in him, as they very evidently aflift in preventing the return of the blood when the artery is in action Between thefe valves and the principal cavity of the ventricle in the Ikate, there is a cylindrical canal interpofed (d), the coats of which have the fame mufcular texture as the ventricle ltfelf ; and their contradion co-operating with that of the ventricle, we are thence led, more evidently than in man, to perceive the ana¬ logy between the ftrudure of the arteries and that of the heart.
The coronary arteries of the heart do not take their rife from the branchial artery, which, like the pulmonary in man, is fpent entirely on their lungs or gills by five pairs of great branches in the Ikate, and by four in the Pifces of Lin-
(a) To be more readily underftood, I (ball generally apply the term* fki. u , "When
manner as is done in fpeaking of the human body ; or, I fhall fuppofe the M t in the fame
Bu, in deferibing the ear and other parts of the he d itfelf I ft , ut ? ^ h«d “PM-
„r » “■ -
JS. " rr;r ■ **- “ ,n *• ’•*->- - ■**» - *■— . * - „ „„
In the Sepia, which has been generally confidered as a filL t- 1. • . ,
nacus, I have, many years ago, difeovered three hearts • of which Ini' f'T reckoned a worm by Lin-
animal, the reader will find an account fubjoined to this Work- * ° ° Kr tunous particulars in the ftrudure of this
(c) See Tab. IT. 40. (</) Tab. I. Fig. 4. t \ t K T f
(0 Tab. I. Fig. 4. and Tab. XXVI. Fig. 1.
CIRCULATION in FISHES* ij
When we take a fuperficial view of the fmall bulk of the gills ; when we re¬ flect, that an organ for reftoring momentum to the blood, fimilar to the left ven¬ tricle of our heart, is wanting in fillies ; and when, further, we confider the ex¬ traordinary fize of the red particles of their blood; we might be tempted, at firft fight, to fuppofe that their branchial artery did not divide into very minute branches, or that it refembled the rete mirabile of the carotid artery of the her¬ bivorous quadruped. But a nearer view will undeceive us. For I have found, that, by the elegant fubdivifions and folds of the membrane of the gills, their fur- face, in a large Ikate, is nearly equal to the whole external furface of the human
Thus in each fide of the body of a Ikate there are four double gills, or gilL with two Tides each, and one fingle gill ; or there are in all eighteen Tides or fur- faces on which the branchial artery is fpread out. On each of thefe fides there are about 50 divifions, or doublings of the membrane of the gills (y). Each divifion has on each fide of it 160 fubdivifions, doublings, or folds of its mem¬ brane ; the length of each of which in a very large Ikate is about one-eighth of an inch, and its breadth about one-fixteenth of an inch (g). So that in the whole gills there are 144,000 fubdivifions or folds, the two Tides of each of which are equal to the 64th part of a fquare inch, or the furface of the whole gills in a large Ikate is equal to 2,250 fquare inches, that is, to more than 15 fquare feet, which have been fuppofed equal to the whole external furface of the human body. When, after a good inje6tion of the artery, a microfcope is applied, the whole extent of the membrane of the gills is feen covered with a beautiful net-work of exceeding¬ ly minute veflels.
As fifhes taint the water they refpire, nearly che fame manner as we taint the air we breathe,4 it appears that fome matter, either ufelefs or hurtful, or both, is carried off from their blood as it pafles through their gills.
When diflilled oil of turpentine, coloured with vermilion, is injected with mo¬ derate force into the branchial artery of a living or recently dead Ikate, fome of the colourlefs part of the oil exfudes upon the furface of the gills. But that thefe are the only paflages by which the hurtful matter efcapes, feems very doubtful ; as, from Dr Prieftley’s experiments, it appears that the colour of the craflamentum of the blood can be changed by the atmofphere, though the craf- famentum be inclofed in an ox’s bladder and covered with ferum.
SECT. II.
We fhall next trace the blood from the gills till it returns to the heart.
In the uppermofl: gill (b), which is fingle, there is but one confiderable vein.
In each of the four double gills there are two principal veins, an upper and un¬ der, joined together by a large tranfverfe canal.
%
(/) Sec Tab. I. Fig. i. 2.
(g) Tab. I. Fig. 3.
The
[b) See Tab. I. Fig. 5. A B C, & c. to W.
i6 Of the HEART, VESSELS, and
The blood iflues from both ends of all thefe veins, but chiefly at the pofterioi
part, between the throat and upper part of the fpine.
From the trunks of the branchial veins the blood pafles diredtly to all the other parts of the fifli, by veflels analogous to the branches of our aorta, and which we therefore call Arteries ; and the gills and liver are the only organs which are not fupplied by them folely.
* • V
/ , ^ J \ l'
SECT. III.
* f I , ' * '
&
In the fkate the branchial veins join together, and then difperfe branches in
I
the following order (i).
The vein A of the uppermofl: gill, which is Angle, is joined, by the canal C, to the uppermofl: vein of the fecond gill ; and then, running inwards and upwards, forms an artery B, which fupplies the parts of the upper jaw, the eye, themofe, the ear, and gives fmall branches to the fore-part of the brain*
From the uppermofl: vein D E of the fecond gill, other fmall arteries F F are fent off to the jaws. After that, a vein K is added, compofed of the under vein H of the fecond gill and upper one I of the third. A little below the joining of all thefe veins, a retrograde artery L, analogous to our vertebral, is fent off to the brain, cerebellum, and top of the fpinal marrow, the branches of which have large and numerous communications with each other, and with the correfponding ar¬ tery of the other fide ; and from them, chiefly, the encephalon is fupplied. Then the trunk M, from which this artery came off, meets at N, with its fellow M, from the other fide ; and, about a finger-breadth lower, there is added, on each fide, a vein. IX, formed t»y tl-ie under vein P of the third gill and upper vein Q^of the fourth*
A bout a quarter of an inch below the meeting of all the above at T, is fent off from each fide, at nearly right angles, a very large artery U, analogous in fome meafure to our fubclavian. A large branch, a, from the root of that artery, fupplies fome parts of the lower jaw ; then running towards the fore-part of the gills, it analtomofes freely with the exterior ends of all the branchial veins (£), after which it fends branches Q^QjQjto the gills themfelves, which feem to me analogous to our bronchial arteries ; efpecially as from the fame part the heart receives its coronary arteries (/). The reft of the great artery, which I have called like to our fubclavian, fupplies the numerous and large mufcles and fins on the fide of the fifli, as far down as the fins near to the anus.
At laft, to the trunk T before-mentioned, is added a large vein X, on each fide which conveys the blood from the under vein S of the fourth gill, and both veins V W of the fifth gill (m) ■ and we are led by it to a great veil'd Y, which now aflumes plainly the office of an artery, refembling our aorta defcendens.
From the fore-part of this trunk two large branches cd, analogous to our cseliac and mefenteric arteries, are fent off to the chylopoietic vifcera ; a fmall branch from which enters the liver, refembling our hepatic artery («).
From
{/) Tab. I. Fig. (w) Tab. I. Fig. 5.
P) VIde Tab- F Fig. 5. a , ct Fig. 4. P R R R R. (//) Sec alfo Tab. III. R S T UV W.
(/) Tab. I. Fig. 4. S S.
)
I
(
CIRCULATION in FISHES;
From the Tides of the aorta the organs of generation and urine are fupplied by fmall arteries eeee, &c. and from the lower part of the trunk are Tent off two lateral branches ff that may be compared to our iliac arteries, and which fupply the mufcles and fins at the lower part of the body.
A middle artery g runs ftraight down into the tail, covered and protected by cartilage, and terminates the aortic fyftem.
F rom the remarkable courfe of the arteries of the heart, and of the bronchial and hepatic arteries, fimilar to that in man, we fee clear proof, that the blood, which, after palTing through the gills, has undergone one circulation, or rather here has paffed through one artery and one vein, is unfit for fome office or offices which are performed by the blood in the heart, gills, and liver.
Nutrition only has been mentioned by authors : but no fully fatisfying reafon has as yet been given, why by one circulation the blood fhould become unfit for this purpofe ; and particularly, why the gills or the lungs cannot be nourifhed, though the whole mafs pafles through them.
SECT. IV.
From the £Xtiemities of thefe feveral arteries, the blood is returned to the
heart, by veins which in general refemble our vena portarum (0) and vense cavae (/>).
When we examine thefe veins more accurately, we find two veil^e cavae, a right and left one, equal in fize and fimilar in fituation, communicating freely by their trunks in the abdomen, and in other places, as in the head, by their branches. In both, the branches are much larger in their courfe than at their terminations ; and they, befides, form confiderable receptacles of blood. For inflance, each of the abdominal cavae has double the diameter of the cavae conjoined at the heart ; and under the place at which the two cavae communicate, there is a large receptacle of blood covered by the ovarium in the female, and by the teftes in the male (y). In like manner, the hepatic veins between the liver and diaphragm form finufes,
the diameter of which is ten times greater than that of their openings into the cavae (r).
_ Up°n the whole, they join in the following manner. The veins from the tail joining with the iliac vein*,, form the bottom of the two venae cavae. Tab, II 2 a Then the veins from the organs of urine and generation are added, 24, 25. At 26 the two abdominal cavae, which are contiguous, communicate freely with each other. At 27, above the diaphragm, and behind cartilages which refemble bur clavicles, the abdominal cavae join with the veins which refemble the branches of our fupenor cava. At 28, 29, 30, veins from the mufcles of the back and late¬ ral parts form a trunk refembling our right fubclaviatt vein ; to which the intef- nal jugular 33, and external jugular 34, are foon added. A little farther in, the right vena cava hepatica 3 1 , terminates ; and this, at 32, is joined to the left vena cava hepatica. The communicating canal alfo receives the blood from a middle
(«) See Tab. III. XX, Y, ZZ, a a, lb , <r, e,/
E
(/>) Tab. II. (?) Tab. IX. V.
lobe
(0 See Tab. II. 31.
/
9
f
t
\
45 Of t’he HEART, VESSELS, and
lobe of the liver; that organ being divided into three lobes. The two cavae, 35, at laft meet ; and, after receiving the coronary veins, 37, of the heart, difeharge themfelves through a round hole with rifing edges, into the back-part of the au¬ ricle of the heart.
Within the external jugular veins, and at the termination of the internal jugu¬ lars, I obferve a pair of valves like to thofe in the veins of the human fubject : At the termination of the renal veins and large branches of the hepatic veins, we find fingle membranes fixed by threads from their edges, refembling the valve of the coronary vein of our hearty and at the termination of the other large veins, efpe- cially near the heart, we not only find the orifices contracted, but doublings at their edges, which have fo far the effect of valves, even in the dead body, that we cannot fill completely all the veins by throwing an inje&ion in at one of their branches ; and, between the auricle and ventricle, valves are interpofed, which perform their office with great accuracy.
SECT. V.
After tracing the blood in its courfe, I compared with each other the coats of the different veffels through which it pafles.
When the large branches of the branchial arteries and veins, or the branches of the aorta formed by the latter, were placed contiguous, they were found to agree very nearly in thicknefs, elafticity, and texture ; nor could I perceive that the fmall branches of the branchial veins differed from the fmall branches of the ar¬ teries, or that any particular place could be pointed out, at which they might be fuppofed to ceafe from performing the office of veins and to begin to do that of arteries. But the coats of their branchial veins, or of the branches of their aorta, feem to differ as much from the coats of the veins which compofe their vena por-
tarum or venae cavae, as the coats of our aorta differ from thofe of our vena> cavae.
• 1
CHAPTER II.
•_ * * * « ' *
' * “ I I ’ 4
f I • » . /
Obfervations on the Circulation of the Blood in Fishes.
FROM reviewing the circulating fyftem, and reflecting on the colour of the parts of fifhes, the following conclufions arife.
AS W£ obferve that ^ particles of the blood are excluded from many parts, as, in white filhes, from moft of their mufcular fibres, which we know have
in us numerous emulating arteries difperfed upon them, it is evident that in them
# . / ‘ V * kl ' »
there
1
k
CIRCULATION in FISHES, 1 9
there are numberlefs colourlefs arteries ; or we find here ftill dearer £roof of the exiftence of fuch arteries, than arifes from the infpe&ion of the human body.
2. When we next confider, that from the circulating arteries of their mufcles* liquors muft be fecreted into the interftices of the fibres, in order to prevent their concretion, and to allow of their ready play upon each other, we fee proof that fecerning branches may be fent off from colourlefs arteries ; and that it is not ne- ceffary, on account of the want of impulfe a tergo in colourlefs arteries, that fe-
creting veffels fhould come dire&ly from thofe that convey red bloody as Dr
• * • /
Haller fuppofed (r).
3. When to this we add an obfervation I have repeatedly made on the blood of animals, to which I had given madder mixed with their food, to wit, that in their ferum, which was deeply coloured, I could not, with the belt tiiicrofcopes, jperceive the colouring particles, and yet that the colour was excluded from their cornea and from their cartilages, we are led to perceive that the exiftence of de¬ fending feries of arteries has without juft reafon been called in queftion by Dr Haller and others (/).
4. As there are few red parts in white fifties, and yet their venae cavae, at their
heart, bear nearly the fame proportion to their aorta or branchial artery as in man, we muft conclude, that their colourlefs, as well as their red arteries, terminate in their cavae. •
Hence, by analogy, it may be allowable to infer, that our colourlefs arteries do not end in our valvular lymphatic veins, but in our cavae ; or that our cavae correfpond with all the arteries which ferve for circulating the blood.
5. From the divifion of the branchial arteries into exceedingly minute branches, we fhould fuppofe, that the force of the ftroke of the heart upon the blood muft be very much broken and loft before the blood gets into the branchial veins ; and, in fadt, I faw no pulfation in the branches of the aorta of a living fkate. Hence, in the firft place, we may infer, that the branchial veins are not made
* f
thick and tough, merely to enable them to refift the vis a tergo .
6. As fo much ftrength and elafticity in the branchial veins are not neceflary for merely refilling the force of the blood, or that more ftrength and elafticity than we obferve in our pulmonary veins were not neceflary for receiving or for merely conducing the blood to the other parts of the body, we muft fuppofe that thefe thick, tough, and elaftic coats, are of a living and mufcular nature, and that the progreflion of the blood through the reft of the body of the fifh de* pends much on their activity.
7. We fhall ftill more readily admit that the mufcular power of the veflels,
and particularly of the arteries, is neceflary for the progreflion of the blood, when, proceeding a ftep farther, we obferve a third circle completed in their liver ; though, from the fituation of their gills, and the membranous nature of their dia¬ phragm, the motion of the blood in their liver is not aflifted by their refpiration, nor does there feem to be any other vicarious external impulfe fitted to forward it. . , . . . ' 1 •”
1
8. Apply-
(0 Ibid. & Elem. Phyf. tom. i. 117, &c.
(s) See Haller Prim. Lin. Phyfiolog. § xU.
I
M OBSERVATIONS onthe
8. Applying to man what we have obferved of the vefTels and circulation in fillies, we in the fird place receive ftrong confirmation of an opinion I have al¬ ways taught, That our arteries are of a mufcular nature ; and that their a6hvity is elfential in circulation, fecretion, and other important offices.
In the next place we will conclude, that the alternate preffure of our diaphragm and abdominal mufcles in refpiration is not, as fome have fuppofed, the principal caufe of the motion of the blood through the liver ; but that the motion of the blood and fecretion of the bile depend chiefly on the mufcular drutdure and ac¬ tion of the branches of the vena portarum. Nay, in the large branches of the mefenteric veins and vena portarum of an ox, I can by diffecdion demondrate a truly mufcular coat, confiding of two didin<d layers. In the external layer the fibres are longitudinal, in the internal they are tranfverfe or circular («).
That refpiration and other external impulfes affid, is highly probable, as the difeafes of the chylopoetic vifcera are mod frequent in fedentary perfons.
9. In their abdominal vense cavae, and alfo between their venae cavae hepaticae and venae cavae, there are large receptacles of blood, and the abdominal trunks of the cavae and feveral of their branches are larger than their terminations.
In the Seal I have difcovered a dmilar dilatation where the venae cavae hepa¬ ticae terminate. As in fifhes the predure of the water upon the gills mud be very much more than the predure of the air upon the lungs of land animals, fuch receptacles were perhaps neceflary when they defcend to a great depth ; jud as in the Seal they are wanted when the refpiration of the air is interrupted by his diving.
/ ‘ . • ✓ > • v >*■
There feems, however, to be reafon for fufpe&ing, that fome other more
latent purpofes are accomplilhed by this dru&ure. This appears from the analogy of the laCteal and lymphatic fydems ; in which we {hall find afterwards there are dill larger receptacles.
10. The lad remark I fhall make is, That, the circulation of the blood be¬ ing carried on in the cartilaginous fifhes in the fame manner as in the odeous or Pifces of Linnaeus, and the whole mafs? of blood paffing through their gills, they miijl breathe regularly and uninterruptedly to furnifh blood to the brain and other organs, or they cannot poffefs the pulmo arbitrarius as is fuppofed by Linnaeus : So that there appears no^ jud reafon for claffing them with the Am¬ phibia.
In the animals which are commonly reckoned amphibious, to wit the tortoife the frog, the lizard, and the ferpent, a part only of the mafs of blood paffes through the lungs. In the frog and common fmall lizard (*), branches are fent off from the aorta ; which, if we may judge from their fize, convey about one third part of the whole mafs. In the tortoife, the ferpent, and fuch of the lizard tribe as have two auricles and ventricles, a greater proportion paffes through the lungs. In the fea tortoife, the heart and large vefTels of which are delineated in Table IV. the blood from the lungs paffes into the left auricle and from it into the left ventricle. From the left ventricle it is tranfmitted, by
tranfverfe
(«) See Tab. III. * (*) Linnaeus* Syft. Nat. G. 122. Sp. 42. and 47.
t
CIRCULATION in FISHES. a f
' ■ , - , . • i. ,
tranfverfe canals or holes in the feptuiri between the ventricles, into the right ventricle, where it is mixed with the blood which is fent from the venae cavae through the right auricle. All the arteries therefore take their rife from the right ventricle ; and the pulmonary arteries are confiderably fmaller than thofe which fupply the place of our aorta (j/).
In all thefe animals, therefore, every part of the body may receive a: confi- derable portion of blood, although the refpiration and free paflage of the blood through their lungs be interrupted. Hence they are not under the fame necefi fity with the mammalia, birds, and fifhes, of breathing frequently, regularly* or alternately ; or they enjoy the pulmo arbitrariusi
CHAPTER III.
. : ' ' - - - ’ . ■
/. ^
\
\ i * > • ,
Of the Glandular Organs and Secreted Liquors in
Fishes.
WE {hall next confider fome remarkable circumftances relating to the glandular organs and fecreted liquors in fifhes.
SECT. L
Of Liquors fecreted on the external Surface of Fifhes t,
* - | , .. '• . - ,
rpHE furface of fifhes, efpecially of fuch as live in the fea* is defended by a A quantity of vifcid {lime ; a great part of which, as has been long known, is poured out in the ofieous filhes by the branches of two du£s which are placed upon their fides. Thefe duds, I have obferved, are continued upon the head and upper jaw; and others of a fimilar ftru&ure are added upon the under jaw (%y
In the Jkate* numerous orifices, placed pretty regularly over the furface, have been obferved by Steno to difcharge this flimy matten Wfth refped to thefe laft, I have remarked fome memorable circumftances. Firft, I have difcovered one very elegant ferpentine canal between the Ikin and mufcles, at the fides of the five apertures into the gills (<z). Farther forwards it furrounds the noftrils ; then it paftes from the under to the upper part of the upper jaw, where it runs backwards as far as the eyes. From the principal part of this dud, in the under fide or belly of the fifti, there are not above fix^or eight outlets 3 but from the
F , upper
(y) See Tab. IV. and the Explanation of it.
(a) See Tab. VI. and VII. ABCDEFGHIKLMN;
(2) See Tab. V. 9. 10. See, to 30,
22 GLANDULAR ORGANS and
upper part near the eyes there are upwards of thirty fmall dudls fent off, which open upon the furface of the fkin. The liquor difcharged from thefe has nearly the fame degree of vifcidity as the fynovia in man.
But befides the very pidturefque dudt I have been defcribing, I have remarked, on each fide of the fifh, a little farther forwards than the foremofl of the five breathing holes, a central part (^), from which a prodigious number of du£ls iffues, to terminate on almoft the whole furface of the fkin, excepting only the fnout or upper jaw. At thefe centres all the dudls are fhut ; and in their courfe they have no communication with each other (c). In thefe two central parts, or on the beginning of the mucous dudls, a pair of nerves (/), nearly as large as the optic, terminate ; and, which is a curious circumftance with refpecl to them, they are white and opake in their courfe between the brain and thefe duels ; but when they divide, they become fuddenly fo pellucid, that it is im- poffible to trace them farther, or to diftinguifh them from the coats of the ducts.
The mucus of thefe dudts is fo extremely vifeid, that it is difficult to fqueeze it out.
Wh en we review the preceding defeription, we obferve,
\ft , Not only a very elegant flru6ture for the preparation of the mucus ; but, . ' • .
idly, Such a fudden change of the colour ~of a nerve, that we are tempted to infer, that its continuation is not merely amexpanfion of the matter of the brain, but that the texture of the nerve is altered in its courfe.
V
^dly, We fee clear proof, that fome, at leafl, of the organs of fecretion, are fo far from being remarkable for the fmallnefs of their nerves, that an uncommon fiiare of nervous energy feems neceflary for them, to enable their veffels to fe- parate and change the liquors they fecrete.
S E C . T. II.
Of the Liquors fecreted into the Cavities of the Cranium , Pericardium , and Abdomen .
it has been long known, that in the greater number of fiflies a watery liqu is found in confiderable quantity within the head, between the dura and j mater : but the nature of that liquor has not been fufficiently attended to, n are its ufes in the offeous fifties fully underftood.
The cavities of the pericardium and peritoneum in all fifties have been fupj fed by authors to be fhut facs.
But in the Ikate and fiurgeon I have obferved fome circumftances, both with refpecl tojthefe cavities and the liquors they contain, that well merit atten¬ tion.
r. In
(.d) Tab. VII. 1 6. 17.
(1) See Tab. Vr. arid VII. 9.9.
(0 Tab. VI. and VI I. 1
o. ir. 12. 13. 14. jj.
SECRETED L I QJJ O R S in FISHES.
1. In the firft place, the liquor within the head (e) is of a faltifh tafle ; not lefs than one fixty-fifth part of it& weight is owing to fea-falt dilfolved in it ;
i
or it contains nearly one half of the proportional quantity of fait dilfolved in our fea-water.
^ ”
2. Within the cavity of the abdomen or peritoneum of a fkate, a great quan¬ tity of a fimilar liquor is to be found, but containing fomewhat lefs of the fait, or about one feventy-eighth part (jf).
3. The great quantity and evidently fait talle of the liquor of the abdomen, which I remarked before I examined the liqdor within the head, led me to look for palfages by which I fufpected the fea-water might get into the abdomen ; and I foon found two holes or palfages, one at each fide of the anus, through which a goofe-quill may be palled (g). One thing, however, ftruck me, that within each of thefe palfages, there is a femilunar membrane or valve, fo placed as to allow liquors to get out from the abdomen readily, but to refill fomewhat their entrance into it (Z>).
4. Further, I difcovered, that in the Ikate the bottom of the pericardium is lengthened into the Ihape of a funnel, whid(i divides into two branches, which are tied clofely to the lower part of the cefophagus, and open into the cavity of the abdomen (i). From the obliquity of thefe branches, and their intimate ad- helion to the cefophagus, neither air. nor water1 can be forced into them from the abdomen : Hence, unlefs we fuppofe that in the living animal they take up the fluid from the abdomen, in the way our puncla lachrymalia take up the tears, which is highly improbable, we mull conclude that they ferve to convey the liquor of the pericardium into the cavity of the abdomen.
5. In the Sturgeon, I have likewife found two holes or palfages at the fides of the anus fimilar to thofe of the Ikate (i) : but, further, I have in this fifh ob- ferved a large funnel on each fide of the abdomen, which at its bottom opens into the middle of the pelvis of the correfponding kidney (/).
When we review the foregoing obfervations* we are led to fuppofe,
1. That the liquor of the pericardium of the Ikate palfes, through the funnel and dudls defcribed, into the cavity of the abdomen.
2. We can have little or no doubt that the liquor, in the abdomen of the fturgeon palfes into the pelvis of the kidney; for we cannot fuppofe that the urine palfes through the holes defcribed into the cavity of the abdomen, as the pelves have large openings into the common cloaca, as in other filhes.
3. In like manner, confidering the funnel Ihape of the lower parts of the ab~ dortien, and of the palfages at the fides of the anus of the Ikate, and difpofition
: ; ' . . ' of
(f) See In Tab. XXXIV. the fize of the cavity of the craniuim
(/) The quantity of fea.falt contained in thefe liquors was, at my requeft, examined by my learned and accurate friend Dr Ru¬ therford, One fifh only was examined. *
(g) Tab. XVIII. 29. ?o. and Tab. XIX. 26. (b) Tab. XVIII. 30.
(0 Tab. II. 22. 22. 22. 23. 23. 23. and Tab. XVIII, 10. Ii. 12. (^) Tab. VIII. fig. 1. Q^R. S. and Fig. i. Q^R,
(/) Tab. VIII. fig. 1. N. O. P.
23
and
H GLANDULAR ORGANS and
i , i ’ » . i ' t . i
' ; • ' • g g gg Lfl
of the valvular membranes, we can fcarcely doubt that the liquor of the abdo¬ men is difcharged through thefe paftages*
4. From the quantity of liquor found within the abdomen both of the lkate and of the fturgeon, and its fait tafte, we feem naturally led to fuppofe, that a great part of that liquor is taken in from the fea by the holes at the tides of the anus ; and that the valvular membranes of thefe holes are intended to prevent folid bodies from getting in. Nay, we would conclude, with flill greater pro¬ bability, that in the fturgeon the holes at the fides of the anus were formed to admit the water, and thofe that open into the pelves of the kidneys ferved ta difcharge it again.
5. But to the above conclufions, I apprehend we ought to add, that a confi- derable portion of the liquor we find in the abdomen is fecreted from the arte¬ ries, as it contains much lefs fait than the fea-water. Nay, perhaps we are not to fuppofe that all its fait enters by thefe holes at the fides of the anus, fince we have found a fimilar degree of faltnefs |in the liquor between the cranium and brain ; which, as no paflages are known to lead diredUy from the fea into the cavity of the cranium, we mult conclude is fecreted from the arteries.
Afterwards when I come to treat of the lymphatic fyftem of filhes, I fhall endeavour to point out the paflages by which the falt-water may readily enter the hydraulic fyftem of thofe fifties.
SEC T. III.
Of Liquors fecreted into the Organs of Digefion .
As. thefe animals are cold, it is more evident than in man, that the gaftric liquor ads as a menftruum upon their food.
In all of them the liver is large, and of courfe the fecretion of bile, co¬ pious ( m ) ; and in all, organs are found which pour out liquors fimilar, pro¬ bably, in their effeds to thofe of our pancreatic liquor. In the lkate, the pan¬ creas is fimilar to the human (*). In all the offeous filhes, fo far as I recoiled, inftead of a pancreas, a number of inteftinula caeca pour out their contents into the duodenum. In the llurgeon, an organ is found in its internal ftrudure fimi¬ lar to thefe inteftinula • but in its outward form refembling the pancreas of the
fltate ; and, which is curious, the whole of it is inclofed in a mufcle, evidently intended to exprefs its contents (o').
Some fads alfo relating to the liver feem to merit attention.
In notes I wrote many years ago, I find the obfervation, That in the cat filh about a dozen hepatic duds difcharge bile into the gall-bladder ( p ). In the eel and falmon, fome of the hepatic duds open into the gall-bladder (q), and others join with the cyftic dud. In the cod, where the gall-bladder is at a diftance
(») See Tab‘ 1X- K- L’ M- N. and Tab. X. («) Tab. IX. 0. P. Tab. XIX. 20.
(/>) See Tab. X. *. (y) Tab. XXVIII. G. H. I.
from
(0 Tab. IX. *.
\
n ■ • I
SECRETED L I QJJ O R S in FISHES. &J
from the liver, a number of hepatic duds open into the cyftic duel (r). Td thefe I would add an obfervation I have many years ago made in the common domeftic cock, that the trunk of the hepatic and cyftic duds have no commu¬ nication with each other in their courfe, and open feparately into the duode¬ num ; but that there are large hepato-cyftic duds.
I obferve, that in all thofe animals the gall-bladder receives directly or indi¬ rectly ducts from the liver. Hence we are led to the inference, that the cyftic bile is not fecreted from the coats of the gall-bladder, as the late Albinus and fome other eminent authors have fuppofed, but that it is derived fiom the
liver.
An attention to the efFeds of cyftic calculi in their defeent through the cyftic duct, ferves to confirm this conclufion. For although it is perhaps merely pof- fible, that when the gall-bladder contains a great quantity of bile, a calculus defeending from it, and {ticking in the cyftic dud, may occafion a fit of jaun¬ dice ; yet I have feveral times found them impacted in the cyftic ,dud of a dead body without any jaundice having appeared before death : And in many other cafes, I have obferved jaundice appear after the patient had been for feveral days or weeks racked with pain *, owing, I apprehend, unqueftionably to the {tones having irritated the cyftic dud before they got down to the common dud.
Whereas if the gall-bladder fecreted the bile it contains, every obftrudion of the cyftic dud {hould create jaundice.
Nay, in a few cafes where {tones very completely obftruded the cyftic dud,
very little bile was found in the gall-bladder.
Laftly, after tying the cyftic dud of a living pig, I did not find jaundice pro¬ duced ; nor did the gall-bladder, after feveral days had elapfed, appear to be more diftended than at the time of the experiment : yet jaundice appeared foon after taking up the hepatic dud with a ligature, and the dud itfelf was obfer¬ ved to be greatly dilated.
S E C T. IV.
Of the Secretions of the Male Or gaits of Generation.
HTHE flructure of the milt in the ofleous fifhes appears to be very fimple : but -*■ in fome of the cartilaginous fifhes, as the Ikate, the apparatus feems flill more complex than in man; for we obferve, in place of the tefticle, a fubftance compofed partly of white matter like the milt, and partly of fmall fpherical bo¬ dies. From thefe an epidydimis is produced, chiefly compofed of convoluted tubes, which terminate in a ferpentine vas deferens ; the under part of which is greatly dilated, and forms, as in birds, a confiderable receptacle or veficula fe-
minalis. (t)*
G ’ Conti-
(r) See Tab. X. E. E. G. G.
\
(/) Tab. XL I. K. L. M. N. O. P. Q^R. S.
2 6
GLANDULAR ORGANS and
Contiguous to the outer fide of the dilated end of the vas deferens, I have found a bag of confiderable fize filled with a green liquor, which is difcharged into the fame funnel with the femen, and probably at the fame time with it (/). As there is no profiate gland, it is probable that this fac fupplies the place
of it. ,
Certain anatomifts, I have been told, contend, that the organs we commonly call veficulce Jeminales are not receptacles of the liquor fecreted by the teftes, but organs capable of fecreting from their inner furface a prolific liquor, which is mixed with that from the tefies. To fuch, the defcription I have given of a veficula containing a green liquor very different from the liquor of the tefies,- which is white, will probably appear a full confirmation of their new dodrine.
Yet I apprehend, that the moft common theory, which fuppofes that the ve- ficulae are to be confidered as being folely or chiefly receptacles of the femen, is well founded.
This new dodrine is, I am told, founded on two obfervations.
*
Firft, on examining the liquor of the veftculae feminales of a man imme¬ diately after death, it was found very different in its appearance from the femen when it is difcharged by a living perfon.
Secondly, that, a confiderable time after .caftration, geldings and oxen had been found capable of generating.
But I would obferve here, that although the liquor of the veficulce feminales is indeed very different in colour from the femen as it appears when difcharged in the ufual manner, becaufe it is then mixed with the vifcid and white liquor of the profiate gland; yet I find it agrees with the liquor in the vafa deferentia as nearly as the cyftic bile does with the hepatic.
In the next place, we certainly know, that, in fome perfons, difcharges of the femen happen very feldom. That the femen may remain in the veficulce femi¬ nales of a caftrated animal a much longer fpace of time, is extremely probable. How long that fpace may be, it will be very difficult to determine.
But fuppofing it were poffible to prove, that, at the time of caftration, there was not a drop of femen in the veficulce feminales, and yet that afterwards the animal was capable of generating, it would not follow from this, that the vefi- culae were not the receptacles of the liquor fecreted in the tefticle. The ut- moft amount of our conclufion would be, that the veficulce feminales, or termi¬ nations of the feminal duds, were capable of fecreting the fame liquor as the be¬ ginnings of thofe duds in the tefticles. Inftances of caftrated animals genera¬ ting are, however, fo very rare, as to render it improbable that the veficulce poftefs fuch a power.
When we throw into the fcale the few following fads, the common opinion will be found to receive great additional ftrength.
I have already obferved the refemblance between the liquor in the end of the vas deferens and in the veficula feminalis ; we may remark a fimilar correfpond- ence in the coats of thefe two parts, and in the cells which thefe form. When
we
✓
(0 See Tab. XII. E. EF. GG. H. I.
I
SECRETED LIQUORS in FISHES. 27
we pour a liquor into the vas deferens, it enters the veficula ftill more readily than a liquor poured into the hepatic dud: does the gall-bladder.
In birds and in the ikate, the dilated end of the vas deferens ferves evidently the purpofe of a veficula feminalis.
In the dog, the veficulae feminales are altogether wanting : yet the ftrudure of their teflis agrees with that of other animals of the fame clafs, or with that of birds ; and no other difference is obfervable, except that the ftrudure of the penis is fuch as renders the copulation tedious.
Upon the whole, it appears that the veficulae &re receptacles of the liquor fe- creted by the teflicles, calculated to infpiffate the femen, and thereby render it
fitter for its purpofe, and at the fame time to prevent copulation from being tedious.
SECT. V.
» 1
Of Secretion in the Female Organs of Generation , and of the Nutrition of the Foetus «
1 * / '
\ . v
» * » •
in the offeous fifhes, the ftrudure of the roe appears to be fimple, and the: ova are fmall.
In the fkate, we find an ovarium, containing large yolks ; two uterine tubes ; an organ in each, from which chiefly the glaire of the egg feems to be fecreted; two uteri, and, within thefe, eggs with horny fhells («).
The beginning of the uterine tubes is tied to the diaphragm, as in the frog: and hence it is probable that the yolks, before they reach the tubes, float loofe in the cavity of the abdomen, as happens in the frog (x) ; yet I have never found an egg of a fkate in that fituation.
The yolk is at laft conveyed by a dud into the fmall inteftine of the foetus, in the fame manner as in birds and lizards (j).
1 * _
t ^ • * -
* * 1 < 1
SECT VI.
♦
Of the fwlmming Bladder of Fifhes.
Hether, in treating of the fecretions of fiflies, an account ought to be given of the fwimming bladder, and the air it contains, is perhaps a fitter queftion than at firft fight it may feem to moll readers.
On this fubjedl, I {hall content myfelf with Hating a few fads and queries, leaving the chief circumftances to be determined by more extenfive examination and experiments than I have leifure for at prefent.
It
<“) See Tab. II. IJ. 16. 16. 17.18. Tab. IX. Q^RR. S. Tab. XIII. EE. FF. (*) Tab. XVII. 0. P, <^R. S. T.
(>) See Tab. XIV. O. P. and Tab. XIV *.
\
4
?
GLANDULAR ORGANS and
It has been long known, that in the flat fillies there is no fwimming-bladdei. In a few long-fhaped fillies, as in the mackrel, I have alfo found it wanting.
It is likewife known, that in many fillies the air-bag communicates by a duel with the cefophagus.
On examining this matter, I have found in a fturgeon a round hole, nearly one inch in diameter, in the upper and back part of the llomach, by which it communicates with a very large air-bag. The hole is furrounded by thin muf- cular fibres, placed between the membranes of the llomach and air-bag, which decuffate at oppofite fides of the hole ; and, no doubt, have the effedt of a
fphindler mufcle (%).
In the falmon, I have found a hole fo large as to admit readily the largefl-fized goofe-quill, leading dire&ly through the coats of the cefophagus into the air¬ bag. The cefophagus in this fifh has a very thick mufcular coat ; but the fibres of that coat do not feem to form a dillindt fphindler around the hole (a).
In the pike, in different kinds of carp, in the perca arenarea, in the conger, duels of confiderable length lead from the cefophagus into the air-bag ; and if, as in the carp, there are two air-bags, the dudl leads to the pollerior bag, from which there is a paffage into the anterior (£).
In the common herring, the under part of the llomach has the fliape of a funnel ; and from the bottom of this funnel a fmall dudl is produced, which runs between the two milts or the two roes to its termination in the middle of an oblong-lhaped air-bag (r.) No valves are found in thefe air-bags.
When we carry our refearches no farther, we very readily conclude, that the air found in the fwimming-bladder has paffed into it through the dudls I have been deferibing. And thefe feem well fuited for the purpofe ; for, as in the common horizontal fituation of the filh their beginning is at the upper part of ' the llomach or cefophagus, we can conceive that the air which we fee them take in at their mouth when they afeend, or that the air which may, by fome more la- tent procefs, be difengaged from the water, is applied to thefe dudls ; and that the filh, by an mllindl of nature, diltinguiflies the irritation of air from that of water, and propels the air into the air-bag, but excludes the water. We cer¬ tainly dillinguilh air from water contained in our intellinum redtum.
But I mull next obferve, that in the cod and haddock, although the air-bag is very large, and its fides remarkably llrong, I have not been able to difeover any communication of it with the mouth, cefophagus, llomach, or intellines. No intermediate dudl is difcoverable by diffection. The air-bag is not enlarged by blowing into the alimentary canal ; nor can we empty the air-bag without burlling it. Further, a red-coloured organ, the furface of which is very exten- five, as it is compofed of a vail number of leaves or membranes doubled, is found on the inner fide of the air-bag of the cod (7/), haddock, &c. : but in thofe filhes where the air-bag communicates with the alimentary canal, this red
body
(3) See Tab. XV. fig. i. 2. 3. («) Tab. XV. fig. 1. and Tab. XXIX. F.
{b) See Tab. XV. fig. 2. Tab. XV *.
(<•) Tab. XV. fig. 3. (rf) Tab. XV. fig. 4. 5,'
I
I
SECRETED L I QTJ O R S in FISHES. 2$
body is either very fmall and Ample in its ftrudure, as in the conger eel 5 or entirely wanting, as in the fturgeon, falmon, herring, carp.
Hence there is fome reafon to fuppofe, that the air may be fecreted from this red body, fomewhat in the way it feems to be fecreted into the fwimming- bladders of aquatic plants, or perhaps into the air-bag of the egg of a bird as the chick grows (*).
This, however, I fliall leave as a mere hypothefis, perfuaded that moft read¬ ers will rather fuppofe that the cod, haddock, &c. have an air-dud, which has as yet efcaped obfervation.
To fuch, another queftion will occur, to wit, What is the ufe of this red body ? Does it, like the gills, receive fomewhat ufeful, or difcharge fomewhat hurtful, to the animal ? And are we to fuppofe that the air-bag not only ferves to render the body of the filh fpecifically lighter, but alfo that the air received into it is of benefit to the conftitution, by adding fomewhat ufeful, or. by taking tip fomewhat hurtful?
C H A P T E R IV.
1
v . * < >
_ - - y ' ,
| I -
\ ' 1 ^ f , * “ . - . ’ - ' 3 1 ' -
A Description of the System of Lymphatic Absorbent
A Vessels in Fishes.
' , ' % * %
■- ^ 1 - 1
* i : ■ • - ^ y " ^ \
IN this chapter, I {hall defcribe the cdurfe arid terminations of the ladeal and lymphatic veflels ; firft, in the nantes pinnati, of which no account has been yet given ; and then in the pifces of Linnaeus* In a fubfequent chapter, I fhall propofe fuch obfervations and experiments as ferve to throw farther light on the lymphatic fyftem and fubjed of abforption in general*
« r
SECT. L
“ I ■,
% *
In the Ikate, my chief example of the nantes pinnati, the trad of the ali¬ mentary canal is remarkably Ihort (/*). When we open the fmall inteftine, we obferve fuch large and numerous valvulae conniventes, that, on a calcula¬ tion, the length and furface of the villous coat is found to be much greater than at firft fight we would fuppofe (<g-).
The principal ladeal veflels are fituated near the large branches of the caeliac and mefenteric arteries and veins ; and the principal lymphatic veflels of the
H afliftant
• t ■ "4 ~ " ' 1 f • • .»
♦ V • ^
(?) The air-bag of an egg is over the top of the vagina of the hen ; and the air it Contains before incubation is taken in from the atmofphere after the glaire is covered by a pellicle#
(/) See Tab. XVIII. and XIX.
(g) Tab. IX. EE.
I
I
/
\
DESCRIPTION of the LYMPHATIC
/
afliftant chylopoietic vifcera, to wit, the fpleen, liver, and pancreas, attend the chief blood- veflels of thefe parts (/>).
The la£teal veflels and lymphatics of the afliftant chylopoietic vifcera are much larger in proportion to the blood-veflels than in quadrupeds, birds, or even in the amphibia : their branches communicate with each other freely and repeat¬ edly ; and, inflead of uniting into one or two trunks, they form a right and left plexus (/), which are continued undiminifhed in flze till they are about to join with the lymphatic veflels of the reft of the body. Neither the la6teal nor the lymphatic veflels are quite cylindrical, but, by being contracted a little in many places, feem to be jointed (/£) : So that we Ihould expect to find numerous valves in their courfe, yet thefe are entirely wanting except at the termination of the whole fyftem.
A cellular reticular fubftance, with which the la&eals freely communicate, is found at the larger curvature of the ftomach (/), but nowhere elfe in the fy¬ ftem.
Purfuing the right and left plexufes formed by the la£teals and lymphatics of the chylopoietic organs, we are led upwards, along the fides and back part of the cefophagus, to the fides of the fpine and outer fides of the inferior venae cavae, and near to large veins covered by ftrong cartilages which refemble our cla¬ vicles, and which therefore may be called Subclavian Veins ( m ). Towards thefe places all the lymphatic veflels of the body are directed ; the lymphatics of the kidneys and organs of generation, with thofe of the tail and inferior parts, afeending ; thofe of the fleflr and fide-fins or wings of the trunk of the body run¬ ning inwards, and thofe of the fuperior parts and of the brain, organs of the fenfes, heart and gills, defeending ( n ).
The branches of the lymphatic veflels form larger angles where they termi¬ nate in their trunks than are found in the circulating veins ; and the fmaller branches are connected by tranfverfe canals (0).
- The large lymphatics of the mufcular organs, near their joining with the la&eals, are colle&ed together in the moft Ample manner, or without forming fuch intricate plexufes as we have feen in the courfe and near to the termination of the la&eal veflels (/>) *, particularly the lymph from the head and thorax is con¬ veyed chiefly by a Angle trunk (q). >
At laft a Angle veflel on each fide of the animal, and in which there is no dilatation or large receptacle of the chyle or lymph, receives all the chyle and lymph, and terminates in the fubclavian vein, very near its joining with the internal jugular vein, or in the angle nearly which thefe two veflels form by their joining (r). The blood is prevented from getting into thefe two veflels by a pair of valves placed at the termination of each (j).
( h ) See Tab. I U. g & c. to q. Tab. XVIII. and XIX. ABC. See. to Z.
(0 Compare Tab. XVI II. with Tab. XIX. I K L, &c. (f) See Tab. XVIII. and
No
xix.befghikl.
(/) See Tab. XIX. C D. and Tab. XX. fig. i. 2. (») Compare Tab. XVIII. X. and Tab. XIX. R. with Tab. II. 28. to 34.
(«) See Tab. XVIII. K L, See. to X. and Tab. XIX. K L to S. v,rTTT .
V°) lab. XVIII. fig. 2.
W SCC ^ XVm’ L' ‘° W- (,) Tab. XVIII. RSTUVW,
(,) S« Tab. XVIII. X. Tab. XIX. R. aad Tab. II. ,6. („ Tab. II. 36. and Tab. XVIII. X. and XIX. R.
I
I
ABSORBENT VESSELS in FISHES. Jf
No glands, like to our Conglobate glands, are found in any part of the lym¬ phatic fyftem of fifties.
SECT. 11.
I Ihall next give a defcription of the lymphatic fyftem of the pifccs of Lin¬ naeus, taken chiefly from the gadus and falmo, but compared in fome paiticu.ar points with other kinds of fifties.
The chief branches of the lacteal veflels of the great and fmall inteftines, and which are fmaller in proportion to the blood-veflels than in the nantes pinnati, run upwards in the mefentery, almoft parrallel to each other, and near the me- fenteric arteries (/). In their whole courfe they communicate by a vaft number of fmall tranfverfe canals («). At the top of the abdomen near the gall-bladder, the lacteals of the ftomach and lymphatics of the fpleen, liver and inteftinula czeca are added (#). The chyle, mixed with the lymph of the afliftant chylo- poietic vifcera, pafles, upwards and towards the right fide, into a large recep¬ tacle contiguous to the gall-bladder, and between it and the right fide and back jpart of the lower end of the cefophagus (_>’)• From the receptacle of the chyle large canals pafs upwards to right and left, receiving in this courfe the lymph from the organs of urine and generation. Thofe on the left fide are chiefly behind the cefophagus (z).
The chyle, mixed with the abdominal lymph, having afcended above the bones which refemble our clavicles, is poured into large cellular receptacles, fituated chiefly between the clavicles and the undermoft of the gills ; and which alfo receive the lymph from all the other parts of the body (a).
Four lymphatic veflels, which terminate in thefe receptacles, and which have their extremities contracted by a doubling of their internal membranes, chiefly merit attention. The firft conveys the lymph from the middle of the belly, from the ventral and peaoral fins, and from the heart (b). The fecond runs up the fide of the filh parallel to the great mucous dud, and brings the lymph from the principal mufcles of the tail and body (c). The third is deep feated, and conveys the lymph from the fpine, fpinal marrow, and upper part of the head (d). The fourth lymphatic veflel, or rather plexus of veflels, brings the lymph from the brain and organs of the fenfes, and from the mouth, jaws, and
gills (<?).
Thefe receptacles may therefore be called the common receptacles of the chyle and lymph. The right receptacle communicates freely with the left by
large canals, which pafs chiefly behind the heart and cefophagus (/).
• From
(;) See Tab. XXII. fig. I. 16. 17. 18. 19.20. (“) Tab. XXII. fig. 2.
(x) See Tab. XXII. fig. i. 21.22. 23. 24. 25. 0) Tab. XXII. fig. 1. 26. Tab. XXIV. W W. and Tab. XXIX. L.
(z) See Tab. XXII. and XXIX. («) Tab. XXII. fig. 27. &c. Tab. XXIV. X X. Y Y. Z. Tab. XXV. Fig. 1. and 2.
0) See Tab. XXV. fig. 2. X. and Tab. XXIV. Y Y. Z. and Tab. XXVII. N.
(c) See Tab. XXIV. a a b, and Tab. 25. fig. 2. S. and Tab. XXVII. M.
(?) See Tab. XXIV. d ef^ and Tab. XXVII. O.
{d) Tab. XXIV. a (/) Tab* XXIV. g fh
3*
EXPERIMENTS on the lymphatic
From each of thefe receptacles in the falmon* a canal runs downwards and inwards, and opens into the upper end of its correfponding vena cava inferior, contiguous to and on the fore and outer fide of the internal jugular vein. The terminations of thefe canals are contracted, and their internal membranes are doubled, fo as to ferve the purpofe of valves, in preventing the paflage of the blood from the venae cavae into the receptacles (g). In the cod kind, the re¬ ceptacles are proportionally larger than in the falmon ; and, befides tranfmitting the mufcles of the gills and their feveral nerves, contain the upper cornua of the air-bladder (Z»).
CHAPTER V.
S ' ' * • ' .
Experiments and Observations on the System of Lym-
phatic Absorbent Vessels of Fishes.
» | ' f ■ * “
, t • ' - * ,
* • * ' ‘ I ,
"I i^RQM the want of valves in the lymphatic fyftem of fifties, except at its
JL termination in the red veins, we can injecft coloured fluids from the large lymphatics into the fmall ; and hence trace the feveral parts of the fyftem much more eaflly and diftin&ly than in the mammalia or in birds. In the nantes pinnati, where, except in the reticular fubftances of the ftomach, the lymph is contained in vefTels nearly of a cylindrical fhape, and remarkably tough, we can trace the lymphatics with ftill greater certainty than in the pifces of Linnaeus : For in the latter, from the weaknefs of the fides of the receptacles of the chyle and lymph, their great fize, irregular fliape, and numerous com¬ munications with each other, a rupture of them, with extravafation and lacera¬ tion of neighbouring red veins, happens frequently ; and as the injected liquors get thereby into the red veins, we are apt to miftake thefe for lymphatic veins.
I have therefore made my experiments chiefly on the nantes pinnati ; and have found, beyond all doubt, that the diftribution of the lymphatic fyftem is uni-' verfal in them : particularly, by injecting the principal lymphatic from their head (/), I have difcovered numberlefs lymphatics in their brain, eye, ear nofe (/£) ; in all which places the exiftence of lymphatic veflels has of late been called in queftion by men of eminence.
V
V ' — ■ 0 '
a. I would next remind the reader of an obfervation I formerly made, That the red veins are, in proportion to their arteries, as large in fifties as in man or quadrupeds, and yet their blood contains few red particles ; and from the veflels
. of
(£) See Tab. XXVI. fig. i. 2. n. xi. Tab. XXVII. S. Tab. XXVIII. M. N. Tab. XXIX. P. O {h) See Tab. XXII. fig. r. 32. Tab. XXIV. O, P. (j) Tab. XVIII. RSTUVW.
(*) Tab. XXI.
ABSORBENT VESSELS of FISHES; 3j
of their mufcles, and of many other parts, thefe particles are in a great meafure excluded : from which 1 concluded, that their colourlefs, as well as their red arteries, terminate in their red veins.
3. In a great number of experiments, by inje&ing penetrating liquors into the arteries and lymphatic veins of fifties, I have found it impoffible to make thefe liquors pafs from the arteries into the lymphatics, or from the lymphatics into the arteries, except where there was a laceration or rupture of thefe vef- fels ; yet I have repeatedly inje£led their red veins from their arteries.
Hence the lymphatic veins do not feem to be the continuation of the lym¬ phatic arteries of fifties : or we are led to fuppofe that, as they do not affifl: di- redtly in circulating the blood, they mult be of ufe by abforbing fluids from the furface, and from the different cavities of their bodies.
• /
4. From a variety of obfervations and experiments, we can convince our rea- fon, that the human valvular lymphatic veins are a fyftem of abforbents ; but in this clafs of animals, I have difcovered that it is poffible to give a decifive ocu¬ lar proof of the truth of that dodlrine, by obferving the effects of injedting fluids from the trunks into the fmall branches of the lymphatic veins.
My firft experiments were made upon the ladteal veffels of the fkate and of the
cod. I found that water, and even air which is lefs penetrating, paffed into the
" • % ■
cavities of the ftomach and inteflines, but with difficulty ; and as I could not, when pufhing my injection, fee the villous coat of thofe parts, I was by no means certain whether the injection was difcharged from the natural mouths or beginnings of thofe veflels, or from the fides of them burfl by the force with which the injection was pufhed. I therefore thought of making my experiments upon a lymphatic from the external furface of the body; and I judged that the great lymphatic from the head and fore part of the fkate (/) would be the fitteft for my purpofe, as it is large and its coats are remarkably ftrong.
I foon obferved that my fuccefs exceeded my moft fanguine expedlation : For although I had no doubt that the lymphatic veins began by open mouths, yet I
conceived that thefe mufl: be fo exceedingly minute, that no clear view could
• • • ' #
be got of them, and that the colourlefs part alone of the liquors injected would exfude. But inftead of this, I found that not only water, but air, milk, quick- filver, and even oil of turpentine coloured with the powder of vermilion, were difcharged upon the furface of the fkin, by a vafl: number of diftind orifices, placed at regular diftances from each other : yet the force with which thefe li¬ quors were injected was very fmall, and there was no extravafation into the cel- lular fubftance any where under the fkin, or in the interftices of the mufcles* On the contrary, the preparations of the parts on which thefe experiments were made, give the moft: perfect and beautiful view imaginable of the vafl: number and extreme fmallnefs of the branches of thofe veflels difperfed upon the fkin, mufcles, brain, eye, ear, &c. no where disfigured by extravafation (w). Nay,
I which
* f ,* « .
} (/) See Tab. XVIII. fig.i.RSTUW. (m) Tab. XXL
A-
V t\ . * N
* jff / ' I * , ¥ x ’ '4
#:• • ’ . * . . ;
•I
I
S
I
• ' •
34 EXPERIMENTS on the LYMPHATIC
which is very curious, and the caufe difficult to affign, the eftufion of thefe li¬ quors upon the furface of the Ikin is made upon the upper or back part only of the fifli, where the Ikin is remarkably tough and fcabrous ; whereas, on the fuppolition of a rupture, the effulion fhould have been chiefly or folely obfer- vable on the inferior part, where the Ikin is thin, fmooth, and much more ten- den From the fmall force neceflary to be ufed in thofe injedions, from the want of extravafation in the cellular fubflance, and from the regular diftribu- tion of the orifices from which the liquor is difeharged on the furface of the Ikin, no perfon ufed to fuch experiments can entertain a doubt that thefe ori¬ fices are the natural beginnings of the lymphatic veins.
The only perplexing circumflances that will occur to him are, how to ac¬ count for their being feen on the upper part only of the fifh, and for their be¬ ing larger there than we would expert, when we confider the moft approved opi¬ nions about the extreme fmallnefs of the mouths of abforbent veflfels.
Thefe difficulties, I apprehend, may be much leflened, if not removed en¬ tirely, by attending to the two following fads.
Firft, within the echinus marinus efculentus of Linnaeus, a large quantity of falt-water is lodged between the inner fide of the fhell and outer fide of the ali¬ mentary canal. On carefully examining the outer furface of the fhell, I have difeovered above two thoufand veflels with orifices or mouths at their beginning, vifible to the naked eye, and furrounded with a hard fubflance, fo that they greatly refemble the human punda lachrymalia. Thefe veflels, after penetra¬ ting the fhell, divide upon membranes into a plexus of branches ; from the op- pofite fide of which other duds are fent out, which terminate at the roots of the teeth («).
There can be no doubt, therefore, that thefe veflels with vifible orifices ab-
« i
forb from the fea the falt-water which is depofited within the fhell.
Secondly, I have found that the water which is contained in confiderable quantity within the fkull of the fkate, between it and the furface of the brain. Contains a large proportion of fea-falt ; for the abforption of which the veflels I have deferibed in the Ikin feem to be appropriated.
Upon the whole, I apprehend it may be concluded, that to the many argu¬ ments which concur in fhowing that the lymphatic veins are a fyftem of abforb- ents, wC may now add the demonftration of fome of the orifices by which they begin in fifties.
' , : , ' ‘ ; , . I ■/ . -■ , r; '
5 . It may be worth while to remark, that from the defeription given of the abforbent veflels of the echinus marinus, which belongs to the clafs of worms, we receive proof, that the abforbent veflels form a diftind fyftem in the worms as well as in the mammalia, birds, amphibia, and fifties. Hence, too, it is highly pro¬ bable a fimilar fyftem will be difeovered in the clafs of infeds, or will be found to be univerfal ifi the animal kingdom.
6. As
(*) 0f thefe abforbcnM and of the other ?arts of thls v«y curious animal, I gave a full account in a paper I read to the Philo¬ sophical Society of Edinburgh ia 176J, which I have annexed to this work.
35
Absorbent vessels of fishes.
G. As no valves are found at the beginning or in the progrefs of the lympha¬ tic veffels of fillies, or in the abforbents of the echinus marinus, we find proof of three very effential particulars :
Firft, That the progreflive motion of the fluids, in their lymphatic ve e s from their fmall to their large branches, does not depend on the external pref- fure of the mufcles, &c. ; for, without valves, this would drive the fluids as
readily in the direction from their trunks as towards them.
Secondly, We are of courfe led to conclude, that the coats of the lymp atic
veffels, however thin they may feem, are truly mufcular.
Thirdly, Although thefe veffels are in life conftantly, or at leaft genera y, filled with fluids, and therefore equally ftimulated in their whole extent ; yet we mull conceive that their adion, contrary to what we obferve of the arteries, mull begin at their orifices, and proceed from the fmall towards the large
branches.
/ * * '
• . • , t i !' ’ , • ,
7. The obfervations I made in a former chapter on the venous receptacles of the red blood, may be applied to thofe of the chyle and lymph. But, further, as lymphatic glands are wanting in this clafs, it may feem, in fome degree pro¬ bable, that thefe receptacles aflift in fupplying their place by the preffure an agitation to which the chyle and lymph are there expofed ; and that perhaps ar- terious fluids are fecreted from their coats, and mixed with the lymph.
8. Our reafon teaches us, that abforbent veffels mull: exift in every the moll: minute part of the body : But when we view a well-injeCled preparation of the laCteal or lymphatic veffels of fillies, we arc ftruck not only with the number of their minute branches, but with the number of their anaftomofing canals ; many of which enter the neighbouring lymphatics at right angles, inftead of being di¬ rected towards the heart ; by which means a net-work is produced, fo very in¬ tricate, that, when we view a fmall part of it only, it is difficult or impoffible to
afcertain what has been the natural courfe of the lymph (o).
By the great number and unfavourable direction of thefe anaftomofing canals,
the flow of the lymph muft be greatly retarded, to ferve purpofes which it is
difficult to afcertain or even to conjecture.
From obferving them, and confidering their effect in retarding the flow of the lymph towards the heart, we fee further proof, that general preffure cannot be a chief caufe of the progreflive motion of the lymph, but that each veffel muft contribute to its progrefs by a well-regulated a&ion.
/
9. Very numerous and large lymphatics are difperfed upon the gills of the
Ikate. To this, when we add that fifties foon die when put into water from
which the air has been extracted, and yet that fuch water is capable of waftiing
off exhaled matter from the gills, and of taking up phlogifton readily (/>), we
are led to the fuppofition, that the gills or lungs not only difcharge hurtful mat¬ ter.
(o) See Tab XVIII. fig. 2- Tab XXI. fig. 2. Tab. XXIII. fig. 2. and 4.
(/>) SeeCavalloon Air, p.485.
36 ' OBSERVATIONS on the LYMPHATICS
* * ' «• ■ / ,
ter, but ferve alfo to take in from the air, which is mixed with the water,
* ' > ,
fomewhat necelfary for life ; the precife nature of which, experiments do not yet enable us to fpecify.
We may, however, obferve, that the colour and quantity of the red particles of the blood, and the heat of animals, are connected with the mode of their re- fpiration ; and that it is as conceivable that the crallamentum of blood immerfed in ferum and inclofed in a bladder, or that blood circulating in the lungs of a living animal, may receive or attract fubtile matter from the atmofphere, as that it may difcharge fuch into it.
S . i
* ■ » ■, I . '
: ■
CHAPTER VI.
Observations on the Lymphatics of the Spleen in Fishes, and on the Uses in general of that Organ.
HT1 HE late Mr Hewfon revived a very-laudable attempt to afcertain by expe-
X riments the ftrudure and ufes of the fpleen. He has defcribed certain
mmute cells in the fpleen unknown to former authors, and fimilar cells in the lymphatic glands.
In a former work, he had reprefented the red particles of the blood as con- Ji mg each of a central part or nucleus included in a veficular, together form- mg a flat body, the lhape of which he compares to that of a fliilling-. He con*
tends, that the cells of the lymphatic glands form the central parts, and that thofe of the fpleen add the veficular.
His arguments are numerous, and his conclufions are drawn with an air of demonflration : Yet I fhall endeavour to prove, that neither his conclufions, nor the facts on which they are founded, ought to be admitted.
1 . It is perhaps not a little queftionable, whether two kinds of red particles
are diftinguifhable in the blood of living animals, very different from each other
in ize and flrape, to wit, the central, and what he calls the full formed flit particles. 1
2. The appearance of cells in the lymphatic glands and fpleen I am well con¬ vinced proceeds from an optical deception, of which Mr Hewfon had no fufni- cion • for I have found, that any organ of the body exhibits that appearance as
1 “d S , °r fl f|>W Mr Mr Falconer h,™
repre cored the particles of the blood about Cxty times the fize of thofe cells
...htn winch, however, they pretended thef, pardcles are contained W
3. i Hewfon tells us, that many central particles are to be feen in the blood conveyed by the iplenie artery, but none in the blood of ,he fplenic veb'
whereas
(?) See my Obfervatfons on the Nervous Syftem, p. 73,
37
,6f the SPLEEN in FISHES.
whereas I have not been able to difcover any difference of particles in the fplenic artery and vein either in a pig or in a fkate. Indeed in both, all the red par¬ ticles appeared to me to be uniform in fize and fhape.
4. Mr Hewfon tells us, that the blood of the fplenic artery coagulates rea¬ dily, but that of the fplenic vein fcarcely at all : hence he infers, that the lym- . phatic part of the blood conveyed by the artery is converted into the veficulai part of the red particles. But although I think I have obferved that the blood of the vena portarum is lefs frequently coagulated, or fomewhat lefs difpofed to coagulate, than that of the venae cavae, yet I cannot perceive that the blood from
the mefenteric veins differs fenfibly from that of the fplenic vein.
5. But his great argument, and which may be confidered as his aigumentum crucis, is, that the lymphatic vefTels of the fpleen in living animals have been obferved to contain the red particles of the blood completely formed. They are therefore confidered by him as dudts from the cells : and it is fuppofed that this circumflance as fully eftablifhes the ufe of the fpleen, as the finding bile m the hepatic dud {hows the fundion of the liver (r).
As a full confutation of this noted argument, I mufl point out three plain
fads. ,, .
Firft, That the lymphatic veffels of the fpleen are nowife remarkable for their
number or fize.
Secondly, That when the fpleen and its lymphatic veffels in a living animal are firft laid in view, their contents are pellucid; and they only receive red par¬ ticles fome time after they have been expofed to the air.
The third fa d, which I learned from repeated experiments many years be¬ fore Mr Falconer’s book was publifhed, and which I mentioned in my lectures, is. That flie lymphatic veflels of any deep-feated organ, whether in the thorax or abdomen, fimilarly expofed to the air and irritation, take up red particles. Hence after opening the cavity of the abdomen of a living animal, and fome time thereafter the upper end of the thoracic duct, I have found many red particles mixed with the contents of that dud. To inveftigate all the caufes of this fad would be foreign to our purpofei but one caufe readily prefents itfelf; I mean, that the application of the cold air irritates and inflames the deep-feated or¬ gans ; and in confequence of the inflammation, there is an effufion of the red matter of the blood into the cellular membranes, whence it is taken up by the abforbent lymphatics ; which too, affeded by the irritation, muft be fuppofed
to abforb with more than common vigour.
6. In fifties, and particularly in the Ikate, Mr Hewfon has reprefented the
red particles of the blood much larger than in man ; and of courfe the cells of the fpleen, in which thefe are faid to be completed, ought to be very eafily feen with the microfcope : but this I have not found to be the cafe. Neither in two or three fkates in which the circulation of the blood was going on, though in a languid way, could I perceive any red particles in the lymphatics of the fpleen •,
K which
(r) See M, Falconer on the Blood, &c. fed. 103^
I
I
38 DISCOVERY of the LACTEAL
' * * '' , N \
which in this animal are, in common with the reft of the fyftem, large, and rea¬ dily appear on opening the abdomen.
Further, the fpleen is in fifties as remarkably dark coloured as in man, and, in proportion to the reft of the body, as large; nay, in the fqualus fquatina, or an¬ gel fifti, I have obferved two large fpleens, one attached to the fmall and the other to the large curvature of the ftomach ; yet there are few red particles in their blood : On the other hand, in the fturgeon, where there is much more rednefs in the flefli, and many more red particles in the blood, than in the cod or fkate, although I have found not fewer than feven fpleens, yet the largeft of thefe, in a fturgeon near fix feet in length, does not in bulk exceed a dried horfe-bean ; and the other fix are none of them larger than a dried garden-pea. Fads which fuit ill with the theory propofed. .
Upon the whole, therefore, Mr Hewfon appears to have left this part of phy- fiology involved in nearly the fame obfcurity in which he found it.
He likewife treated with ill-placed ridicule the common opinion, that the fpleen is fubfervient to the liver: For even fuppofing that one ufe of the fpleen had been, as he contended, to complete the red particles of the blood ; ftill, as its venous blood palled not into the vena cava, but into the vena portarum and livei, which we cannot fuppofe to happen in vain, it would have followed, that the fpleen was alfo fubfervient to the liver, althaugh we fhould not have been able to Ipecify the particular nature of the fervice it performed.
CHAPTER VII.
.* ' • * . 1 . , . * ,
; •
' ■ * ■ V ' # * .
Of the firft Discovery of the System of Lacteal and
Lymphatic Vessels of Fishes, Birds, and Amphibious Animals.
I .Shall take this opportunity of eftablifhing, in a few words, my claim to the
firft difcovery of the exiftence of the lacfteal and lymphatic fyftem in birds
and amphibious animals, as well as in fifties, in oppofition to the pretenfions of the late Mr Hewfon.
In a paper I publifhed in 1770 (1), I proved, “ That in 1758, I obferved a
“ Vcffd m the mefentei7 °f the common cock, which I fufpccted to be the “ trunk receiving the lacteal velfels.
„ " Ap,il wlI“ trea,'nS in my Con* of Leftura of Comparative
.. f iTm 3 “Ck What looked like eollapfed, and
„ °(|‘c|c“ ' CO‘°"r- whlch f"med “ Mminate at the back-bone between the
(/) State of fads concerning the paracentefis of the thorax
on
account of air effufed, and lymphatic veffels
in oviparous animals.
and LYMPHATIC VESSELS*
I not only mentioned but fhowed thefe publicly to the ftudcnts of anatomy; and I at the fame time faid, that Di4 Cullen had lately told me that Mr John Hunter had feen lymphatic veffels on the neck of a fwan : And from the two obfervations conjoined, I concluded that fowls had ladeal and lymphatic veffels like our own.
“ Next winter, on April 23d 1760, I difcovered lymphatic glands on the <c neck, blew them up, and valvular lymphatics from them, terminating in the “ ends of the jugular veins.”
After fhowing thefe publicly to the ftudents, I repeated what I had men¬ tioned the preceding winter, but now fpoke with greater firmnefs concerning their ladeal veffels, as I always confidered the ladeal and lymphatic veffels as different branches of the fame general fyftem. Thus in 1757, I had treated of both under the name of Verne Lymphatics Valvulofie (7).
The following day, to wit, April 24th 17 60, “ I difcovered a whole fyftem of cc ladeal and lymphatic veffels in a fkate fifh, running towards the heart on the “ left of and above the vena portarum ; and from thefe the auricle of the heart “ was blown up. They are proportionally larger, but have fewer valves than “ in man.” , -•
This obfervation being made in the forenoon when diffeding for the fubjed of a ledure on fifties, was of courfe mentioned publicly to the ftudents that day.
In the fummer of the year 1761, I gave to a dozen living cocks by the mouth different kinds of food, and the food of fome of them I tinged with madder, faffron, rhubarb ; or I injeded tinged liquors into their intefiines by a hole I cut in them, without obferving that thofe coloured fubftances entered their ladeal veffels.
In the fame fummer I repeated my obfervation of the lymphatic veffels and glands in the neck, and noted their appearance as follows.
“ In the neck, I obferve very diftindly lymphatics, which pafs through feve- “ ral glands like to our glandulae concatenate, and open into the bottom of the
internal jugular vein. If a hole is made into the undermoft: gland, and air « blown in, the vein is immediately filled with the air (u)”
In fummer 1 765, I difcovered ladeal veffels in the mefentery of a turtle; and after injeding the mefenteric arteries with red wax, and their correfponding veins with yellow, I injeded the lymphatics with quickfilver.
I demonftrated this preparation, which I ftill preferve; publicly the following
winter ; and a drawing of it was then made by Dr Palmer, now phyfician at Pe-
*
terborough in England. An engraving from this drawing was publifhed in my date of fads, and is republifhed in this work (x).
From 1759 to the prefent year, it has been my pradice, in my courfe of ledures, firft: to defcribe what I had obferved refpeding the ladeal and lympha¬ tic veffels in thofe animals ; and then to point out in the mefentery of the com¬ mon cock the ladeal veffels, and in the neck the lymphatic veffels and the
glands
( t ) De Venis Lymphaticis Valvulofis, 1757.
(a) Next winter Mr Hcwfon attended my courfe of leftures.
\ . ’
(x) See Tab. XXX.
I
*
40 DISCOVERY or the LACTEAL
glands through which they pafs, before they terminate in the internal jiigulai veins. Nay, as often as I had a little time to fpare for the diffe&ion of the parts, I inflated the lymphatic veffels and glands of the neck ; after which, I handed to the ftudents thefe diffe&ed parts laid on plates, that fuch as chofe might take a nearer view of them. I likewife have conftantly, on this occafio * handed around my preparation of the lacteals of the turtle injedted with quick-
filver.
Much later, to wit, in October 1768, Mr Hewfon prefented to the Royal Society of London an account of the lymphatic fyftem in birds ; and in a note added, he fays, he had fo long ago as in the winter 1763-64 obferved ladeals
in a turtle. ' ' '
In a paragraph fubjoined to the above account, dated December 3. *7^^j
adds, That fince the above paper was put into the hands of the fecretary, he has difcovered the fame fyftem in fifti ; and has likewife been fo fortunate as to pro¬ cure a turtle, whofe lymphatic fyftem he has traced out, and, has got delinea¬ ted.
Accordingly, in June 1 769, he prefented to the Royal Society an account of the lymphatic fyftem in amphibious animals and in fifties.
Not contented with the merit of having merely profecuted the particular branches of the lymphatic fyftem in fome of the oviparous animals, Mr Hew- fon thought proper to afliime the title of their firft difcoverer ; endeavouring to perfuade his readers, that although the paragraphs above quoted, the authenti¬ city of which he could not venture to call in queftion, proved that I had per- fuafions and opinions of their exiftence ; yet they did not prove I had in reality difcovered them. And, to give colour to thefe pretences, he has ventured to publifh notes which he thought fuited his purpofe, taken indeed by fome very refpe&able ftudents who had attended my le&ures.
But though thefe notes are palpably erroneous as well as imperfect ; and that the principal of them, particularly the notes of Dr Morgan, who attended my courfe of
lectures at the fame time with Mr Hewfon, are not taken from my Lectures on
* * *
Comparative Anatomy when I accompanied my defcriptions with diffedion and demonftration, but from a more early part of my courfe, in which, whilft treat¬ ing of the lymphatic fyftem in the human body, I ufed to mention the lympha¬ tic fyftem in the oviparous animals in a curfory way only ; yet even thefe, when compared with the preceding extrads, lead to conclufions very oppofite to thofe Mr Hewfon has drawn ; for they plainly fhow that he mifreprefented the fol¬ lowing very material points.
Firft, Becaufe after fummer 1761 I told the ftudents that I had not obferved coloured liquors enter the la&eal veffels of birds, he reprefents me as acknow¬ ledging I had never feen the la&eal veffels; yet he knew that, for three fuccef- five years preceding that time, I had fliown collapfed bluilh veffels in the me- fentery of fowls, different from the branches of the mefenteric artery and vein. He faw me demonftrate thefe in the winter 1761-2 ; and he muft afterwards have
certainly
And LYMPHATIC VESSELS. 4*
certainly known, as I did, that the vefiels I then, and every year fince, pointed out, were in reality the ladteals of fowls. Nay, before he publifhed, he himfelf had found by experiment, that the chyle in the ladteals of fowls was always co- lourlefs ; and therefore he knew, that my not feeing coloured chyle was no pi oof
that the vefiels I had feen were not the ladteals.
Secondly, Mr Hewfon, upon the credit of what he knew or might have known to be in Dr Morgan’s notes, has aferibed to Mr John Huntei a difcoveiy of mine in 1760 ; which, fo far as I know, that gentleman never aflbmed, and from which the exillence of the valvular lymphatic fyftem in birds was proved, to any perfon who underftands the fubjedt, beyond all polfibility of doubt or de¬ ception : I mean my having, in 1760, firft difeovered conglobate glands at the lower part of the neck of fowls limilar to our glandulse vagae, and having infla¬ ted valvular lymphatic vefiels entering thefe at their upper, and coming out at their lower part, to terminate in the internal jugular veins.
Mr Hewfon’s arguments, by which he pretended to fhow that I had not anti¬ cipated him in the difeovery of the ladteals in fifties, are equally unfortunate.
That the reader may not think I mifreprefent them, I {hall ftate them in his own words. “ Next (fays he) as to the ladeals in fifh. To prove that he (Dr Monro) had found thofe vefiels eight years ago, he (Dr Monro) tells us, that in a note taken from the diftection of a fkate on April 24th 1760, he has faid,
< He had difeovered a whole fyftem of ladteals and lymphatic vefiels, running ‘ towards the heart, on the left of and above the vena portarum ; and from
< thefe the auricle of the heart was blown up. They are propoitionally larger,
* but have fewer valves than in man.’
C( Nbw (continues Mr Hewfon), I will take upon me to fay, theie is nothing in this note which proves whether he had inflated a ladteal or a vein : For what he fays of the fituation of the vefiels, and of his blowing up the heart, » is equi¬ vocal. The only part of the note which appears to charadterife the lacleals is in reality a miftake ; that is, where he fays they have valves."
In anfwer to all this, I would obferve two plain fads. The firft of which is, that the red veins of the mefentery in fifties, as well as in man, do not lead to the heart, but to the vena portarum. When therefore I found that the vefiels I inflated led directly to the heart, I knew them to be for certain the lac-
teals. " ,
In the next place, the vefiels I inflated were in their appearance totally differ¬ ent from the red veins. They formed a great plexus, or what I have called ^ a whole fyftem of ladeals and lymphatics running towards the heart ; were <c larger, and appeared to have fewer valves than in man. But Mr Hewfon exclaims they have no valves ; and therefore would infer that I had not feen their ladteals. But fuppofing they had no valves, it would by no means follow that I had not inflated their ladteals ; becaufe they are in reality not cylindrical vefiels, but are jointed; and of courfe I judged, from the analogy of the human
9 if '»■ ■
body, that they were valvular.
Further, it has appeared, that within the lacleals of the fkate there are cellu-
L Hr
I
42
DISCOVERY of the LACTEAL
lar receptacles and membranes of a valvular nature ; and that, at the termination of the lymphatic fyfiem of fifhes in the red veins, the place of which we have found Mr Hewfon had not been able to trace (j), there are valves exactly like to thofe in the human body, and which perform their office in the mod; accurate manner.
I fhall fubjoin two letters from phylicians of diftinguifhed character, who attended my lectures at critical periods, to wit, Dr Charles Richardfon phyfi- cian at Kingdon in Jamaica, and Dr Adam Kuhn phyfician and profeffor of materia medica at Philadephia.
Dr Richardfon ftudied phyfic in this univerfity from 1755 to 1763, when he received his degree of Doctor of Phyfic, and was confidered by all the pro- feffors as one of the mod fenfible and intelligent candidates who had ever come before them, and at Kingdon in Jamaica is univerfally edeemed. He had attend¬ ed my father’s courfes in 1756-7 and 1757-8, and my three fird courfes, to wit, I759"^°> 1760-1, and 1761-25 ifi the lad of which Mr Hewfon was prefent. As the time of his attendance was fo very critical, I wrote to him in 1769, when Mr Hewfon claimed the fird difcovery of the lymphatics and ladteals in birds and fiffies. As I got no anfwer then, I wrote again two years thereafter, defirmg him to declare what he remembered to have heard or feen here concern¬ ing the lafteal and lymphatic veffels of birds and fifhes. The following is a literal copy of his anfwer.
((
Sir,
k
cc
cc
cc
cc
cc
cc
cc
cc
cc
cc
cc
cc
cc
You defire me to appeal to my notes and memory, to do you juftice with regard to the prior difcovery of the ladeals and lymphatic velTels (in birds and fifh) to the late Mr Hewfon. My manufcripts I had the misfortune to lofe many years ago : however, it is frefli in my memory, that I was not only as much convinced of their exiftence in both, before I left the univerfity of Edin¬ burgh, as I am at prefent ; but that in the year fixty-three I demonftrated them on the mefentery of a live lhark to Mr Gilbert Turnbull, then my mate
in the Speaker Eaft Indiaman, and to feveral other gentlemen prefent • and named you as the difcoverer. * ’
“ UP°n the reCeiPt of y°ur Ietter> 1 wrote to Mr Turnbull and two more friends upon this fubjecl, whofe anfwers have not as yet come to hand •
which is the reafon I have fo long delayed writing to you. Thev can nr. J
be of little fervice when they do come, as poor Hewfon’s death puts an end
to the difpute ; which I am forry to fee terminated in that way, both upon your account and his. ^
“ This wiil introduce t0 your acquaintance Mr Richard Trower, who pro- pofes to complete his medical education in Edinburgh,” &c.
“ I am, &c.
“ Kingdon, Jamaica,") May 4. 17 76. 3
“ For Dr A. Monro.”
“ Charles Richardson.
Afte
0) Mr Hewfon, on the Lymphatic Syltem, p.9,. defcribes « a velfel, the termination „f ,k . . , , jogular vein juft below the orbit,” whereas the real termination is in the v£na, „„ o e 'jhok g»,ng into th,
Tab. XIX. R. Tab. XXVI. fig. 2. 3. and Tab. XXVIII. M. N. ^ Tab’ U> 3<5' Tab‘ XVIII. X
1
After Mr Hewfon’s Appendix was publifhcd in 1772, I wrote to Dr Kuhn^ alking his teftimony ; for as the Dodtor had been with Linnaeus before he flu- died here, and was particularly attentive to natural hiftory, I thought he would recollect what he had feen more particularly than thofe ftudents who attend chiefly to practical fubjedts. He ftudied here in 1765-6 and in 1766-7, and took his degree of Dodtor in 1767. His anfwer is literally as follows :
“ Dear Sir,
“ I am under infinite obligations to you for the Treatife on the Lymphatics “ you were pleafed to fend me, as I never could get the book in this country ; and when I left Europe, not a copy could be purchafed on any account.
“ The flate of fadts between you and Mr Hewfon mult convince even preju- dice that the honour of the invention is due to you. There are feverals in “ this country who are convinced of it from attending your courfe of anatomy^ “ My own teftimony is not of the importance with fome who were in Edin- “ burgh before me ; but I remember well your demonftrating thofe veflels in <c birds and fifli publicly in your ledtures, at a time numbers came annually “ from London, who faw them at your theatre for the firft time.
“ Mr L.” &c.
Philad. 7 July 23. 1773.5
“ I have the honour to be, &c.
“ For Dr A. Monro.”
“ Adam Kuhn.
5
CHAPTER VIII.
\ , '
\ ' v " „
Of the Brain and Organs of the Senses in Fishes.
E C T.
Of the Brain in Fijhes , and Nervous Syjlem in generah
THE brain of fifties is fenfibly fmaller in proportion to their body than in the mammalia or in birds ; yet the nerves it fends off are as large in pro¬ portion to the feveral organs as in thofe two clafles.
In it we find the like principal divifion into brain and cerebellum ; and thefe are hollow, or have ventricles within them.
The
\
I .* / A I
44 BRAIN and ORGANS of the
The fubdivifions of the brain and cerebellum, or their tubercles, and lobes, are more numerous than in the fnammalia or birds ; and in the vaiious genera of fiffies, the differences of thefe are fuch, as to fhow the vanity of attempting to determine the office of each lobe or tubercle of the braim
- . / i '
Ganglia are wanting in their nerves.
In one genus of fiffies, the gadus, I have found fpheroidal bodies between the dura and pi a mater, and covering the greater part of their nerves, like a coat of mail, in their courfe towards the organs to which they are deftined. That this obfervation may be intelligble to the reader, I have fubjoined Tables repre- fenting them (%), which I formerly publilhed in my work on the Nervous Syftem.
• t
After thefe few general obfervations on the brain, we fhall proceed to confidei the organs of the fenfes, and particularly the nofe, the ear, and the eye ; for on thofe of touch and talte I find little or no room for remark. ,
; SECT. 11.
' V ■ s , • f '
Of the Organ of Smell in Fifhes *
* ■ *. • . t \ ' *
■ i .
TN all fiffies, external openings or noflrils for fmell are very evident, generally two on each fide in the offeous fiffies («), which, on each fide of the head (£), lead to a complex organ, the furface of which is of confiderable extent ; and upon them a pair of large or olfa&ory nerves terminates, with the addition of fome branches from nerves refembling our fifth pair (^). In fome fiffies, as in the hadd6ck, I have obferved that the olfactory nerve, in its courfe between the head and the nofe, paffes through a cineritious ball (V), refembling the cineri- tious matter conne&ed in our body to the olfactory nerve within the cranium.
There can therefore be no doubt that they enjoy the fenfe of fmelling : nay, there is great reafon to believe, that, fuited to their furrounding element, they are much more fenfible of odorous bodies difTolved in water, and applied by its medium, than we ffiould be, if the application of the objed was to be made to our organ of fmell by the fame medium.
(2) See Tab. XXXI. XXXII. XXXIIT. (a) Tab. XXXI. fig. i.
( b ) See Tab. II. u. Tab. XL. fig. u and z. (c) Tab. XXXI. 0 O. '
{(!) See Tab. XXXI. fig. i. K.
SECT.
SENSES in FISHES;
4$
5 E
T,
III.
Of the Ear in * Fijh es.
§ I. Of the Ear in the Cetaceous Fijhes .
/■ .
TT is well known that the eir of the whale-kind refembles that of man ; and feveral authors, particularly Dr Tyfon and Dr Camper (e), have publifhed an account of the feveral parts which compofe it : but I have not been able to procure either of thefe works. I obferve, from the Commentarii Liplienfes that Dr Camper denies that they have femicircular canals ; a circumftance in which I apprehend this eminent author to be miftaken. He is alfo uncertain whether they have an Euftachian tube. I {hall for thefe reafons, as well as for the fake of connection, give a fhort account of what I have obferved in the dif- feCtion of the phocaena, one of the cetaceous order.
On each fide of the head there is a round hole (g), fcarcely large enough to admit the head of a fmall pin, which is the beginning of a long meatus audi- torius externus (Ji) ; at the bottom of which we find a concave membrana tym- pani (i). The membrana tympani is conne&ed to the bottom of the cavity of the tympanum by a chain of fmall bones, tied together by a reddifh-coloured membrane. The innermoft piece, analogous to our {tapes, has evidently a mufcle connected to it (/£) ; a large nerve or portio mollis divides into two branches, and then enters the bone at the bottom of the cavity of the tympa¬ num or os petrofum (/) : and following one of the branches of the nerve, we are led to the cochlea, which is divided by a feptum into two fealae ; each of which contains a reddifh-coloured tube, that is eafily feparable from the ofteous canal which contains it (m).
Following the other branch of the nerve, I obferved part of the femicircular canals ; the membrane of which is very thin («), 'and adheres to the bone which
contains it. * ' ,
The cavity of the tympanum is remarkably large, and communicates freely
with other cavities which are analogous to our frontal, fphenoidal and maxillary finufes (0).
A tube, fimilar to our Euftachian tube, or iter a palato ad aurem, begins to-
M « wards
(<?) Tyfon on the Phocxna. Camper a£ta Hariem. tom. ii. et xvii. in 1765 and 177 6. (/) Com. Lipfiens. vol. xvii. p. 460. (^) See Tab. XXXV. fig. 1. F.
(/;) Tab. XXXV. fig. 5. F G.
(7) See Tab. XXXV. fig. 5. I. and fig. 6. X. (/) See Tab. XXXV. fig. 7- T S.
(*) See Tab. XXXV. fig. 8. X.
(k) Tab. XXXV. fig. 6.KLM.
{fit) Tab. XXXV. fig. 8. U W. and fig, 9. W YZ. (*) Tab. XXXV. fig. 6. N 0 P QJRi
I
I
*
I
/
46 BRAIN and ORGANS of 'the
wards the lower end of the fiftula, through which the animal refpires ; and, con¬ trary to what we obferve in man and quadrupeds, it gradually enlarges as it runs back towards the cavity of the tympanum, in which it terminates (/)•
While, therefore, thefe animals float on the furface of the ocean, imprellion is made on the feveral parts of their ear in the fame manner as in man.
The remarkable difference of the flze of the caverns which, in place of the cells of our maftoid procefs, communicate with the cavity of the tympanum, leads us to confider. Whether the effedt of the found upon the ear be increafed by that circumftance ? or. Whether the chief ufe of thefe caverns may be to * render the head fpecifically lighter, and, like fwimming-bladders, to make it rife more readily to the furface of the fea ?
• As the entry into the external meatus auditorius is fo very fmall, there is
/
reafon to fuppofe that the animal can {hut it when it dives to a confiderable depth, and when the weight of the water might have been in danger of injuring the membrana tympani. And from obferving the fmallnefs and ftru&ure of the mouth of the external meatus auditorius in the whale, divers may perceive the neceflity of plugging the ears accurately, in order to prevent the overftretching
of the membranes of the drums.
r . * , . < . ■ - 1 '
v ; , . 1 • 1 . / ■ 1 . . ' - . ”
• 1 • ’ \
§ 2. Of the Ear in Amphibious Animals , and particularly in the Sea Tortoife or Turtle .
Before I proceed to give an account of the ftructure of the ear in the nantes pinnati and pifces of Linnaeus, I {hall, in a few words, defcribe the ear in the intermediate tribe of the amphibious animals, taking the fea tortoife or turtle as my chief example of the clafs.
In this animal, as well as in the frog and moft others of the clafs, there is no external ear nor meatus auditorius extemus ; but we find a large Euftachian tube on the back part of the roof of the mouth, near to the articulation of the under jaw with the upper. This tube has a winding courfe behind the condyle of the upper jaw, and leads to a large cavity, refembling (7) our cavity of the tympa¬ num (r), covered by the lkin of the temple and a tough fubftance with a thin
cartilage on its inner fide ; the whole of which taken together are nearly one fixth part of an inch in thicknefs (s).
To thefe teguments a cartilaginous body, nearly of the fize of a fmall probe, and upwards of three quarters of an inch in length, is conncfted ; and paffes, firft to the bottom of the tympanum, then through a bone, and through another fmaller cavity, in which a watery humour is lodged ; and at the bottom of which the cartilaginous body is connected to a membrane which fills a hole (/).
Within that membrane or hole a third cavity is found, which lodges three
femi-
(/>) See Tab. XXXV. fig. 4. O. fig. J. L M N.
(r) See Tab. XXXVI. fig. 2. B. fig. 3. B.
(0 Sec Tab. XXXVI. fig. 2. E. fig. 3. E F. fig. 4, B.
(?) Tab. XXXVI. fig. i.HI K. fig. 2. C. (/) Tab. XXXVI. fig. 2. A. fig. 3. A.
/
t
I
4 1
SENSES in FISHES,
femicircular canals, to wit, an anterior, a pofterior, and a middle horizontal canal (u), and alfo a fmall fac, which contains a foft cretaceous fubftance (w).
The femicircular canals contain, and are furrounded by, a vifcid watery hu¬ mour.
On the membranes of thefe canals, and on the fac, nerves are difperfed (x).
When we compare the parts in this animal with the human ear, the cartilagi¬ nous body feems to fupply the place of the fmall bones of our ear ^ a<n t e membrane to which the inner end of it is connected feems analagous to the
membrane of our foramen ovale.
The fac containing the cretaceous matter, with the three femicircular canals and nerves difperfed upon them, refemble the labyrinth of our ear.
' * v ■*
• ' / 4 ■ •
I ’ . . , 4
• A , * \ f
§ 3* Of the Ear in the Cartilaginous and OJfeous Eijhes .
v- - i # ) i
The ftru&ure of the ear in the cartilaginous and ofleous fiflies has been fc> little examined, till of late, that, for upwards of two thoufand years, it has been a queftion whether they poflefted organs appropriated for hearing.
Swammerdam (y) mentions a wonderful labyrinth of the ear in Mies \ but moft anatomifts fince his time contented themfelves with pointing out, as the organ of hearing, facs at the fides of the brain of the moft common fifties con¬ taining ftony fubftances, without pretending to fhow external paflages leading to thefe facs, or the nerves or medium by which thefe facs were connected with the brain of the animal.
About the beginning of the year 1779, the learned and accurate Di Soem¬ mering, now profefibr at Cartel, and who at that time did me the honour of at¬ tending my courfe of lectures, told me, that the ingenious Dr Camper, in a letter he had received, mentioned his having difeovered femicircular canals in the ears of filhes. I therefore determined to look for thefe when I fhould come to that part of my courfe in which I treat of Comparative Anatomy > And ac¬ cordingly I found, and fliowed to the ftudents, in the month of April follow¬ ing, femicircular canals both in the Ikate and in the cod.
In the following month of May 1779, I traced the communication of the feveral canals of the ear with each other, and the diftribution of the nerves upon them ; and was alfo fo fortunate as to difeover the entry into the external ear of the Ikate, its concha, meatus auditorius externus, and its communication with the interior canals : All which I have fince annually demonftrated to the ftudents in my courfe of lectures.
In the month of Auguft following, I fliowed to the Philofophical Society of this place the tables of thofe parts in the Ikate and cod which I now publifli,
alone with the tables which reprefent their circulating and abforbent veflels.
Since
(a) See Tab. XXXVI. fig. 3. G H I. (™) Tab. XXXVI. fig. 4. C. (*) Tab. XXXVI. fig. 4- *>•
(y) Swammerdam, Bibl. Natur. p. ui.
#
48
BRAIN and ORGANS of the
Since that time, I have received a Work by M. Geoffroi, on the Organ of Hearing of Fifties and other Animals, which was read to the French Academy in 1753, but was not publiflied till 1778; and find that Dr Camper and M. Vicq. d’Azir, previous to the publication of M. GeofFroi, had given an ac- account of many difcoveries on the fame fubjedff, which they illuftrate by tables (%).
In the works, however, of thefe authors, the communication of the canals of the ear with each other has not been fully traced. Little attention has been paid to the nerves which fupply them ; and a very principal part, the external meatus auditorius, has entirely efcaped their obfervation *.
I fhall therefore proceed to give a defcription of the ear ; firfl in the cartilagi¬ nous flat fifties, and then in fome of the oblong-fhaped cartilaginous and in the ofleous fifties* After which, I fhall give an account of a few experiments I have made on hearing in water.
§ 4. Defcription of the Ear of a Skate .
In the back part of the occiput, near the joining of the head with the fpine, two holes (a), not larger than to admit the head of a fmall pin, are found at the s diftance of an inch from each other in a large fifh. Each of thefe leads into a capacious winding canal or concha, which defcribes nearly a complete circle (£). The two conchae are feparated from each other by a thin partition (c). Each concha terminates in a funnel, from which a fmall cylindrical canal or meatus auditorius externus is continued (J). The meatus is lodged in a hollow left between two thick cartilages ( e ) ; and as there is no membrana tympani, it opens into a large fac, which contains a white or opake matter, with a quantity of clear watery-looking, but vifcid, matter (/). The white fubftance is foft and cretaceous, effervefcing violently with vinegar ; has a regular Ihape ; and yet, in the meatus auditorius externus and concha, generally fome portion of a fimiiar matter is found, as if part of it palled off by the meatus, or was fome- how neceffary for communicating the impreffion of found to the bottom of the ear. •
' > On
. • „ V , y , . , t •
(z) See Ada Harlem, tom. xvii. 1762. et Mem. de Math, et de Phyf. pres-a l’Ac. R. des Sciences, tom. vi. et t!1. I774.
* M. Geoffroi fays, “ L’orgape de l’ouie de la raye ne paroit point du tout a l’exterieur, et fon entree n’eft point
« aifee a decouvrir. Cachee fous des mufcles, elle eft placee proche les condyles, a leur partie laterale externe . £n
“ la fuivant a l’interieur, on voit qu’elle donne nailTance a deux canaux; l’un fort court, qui penetre dans la Cavite” du “ veftibule, une fente longue, irreguliere, dont les bords font comme dechires,” & c.
And p. 93. Du trou auditif . reconvert des mufcles et de graifle,
Dr Camper, Mem. de Math. tom. vi. p. 194. denies that there is an external opening: ** L’organe de l’ouie de la raye “ n’a done aucune communication avec fair de l’atmofphere ; mais il eft enferme,” & c.
And M. Vicq. d’Azir, tom. vii. p. 20. fpeaking of the cartilaginous fillies or nantes pinnati of Linnsus fays « L’or-
** gane de l’ouie na point, che’z eux, d’ouverture exterieure.” * 11
(a) See Tab. VII. fig. i. fig. 2. A A. fig. 3. 4. 5.
(c) See Tab. VII. (1 1 ) Tab. VII. fig. 2. de. fig. 3. 8.
(/) Tab. XXXVII. fig. 2. 1 8. and fig. 3. ah.
{b) Tab. VII. fig. 2. B C. fig. 3. 6. 7.
(el Tab. XXXVII. fig. 2. 16. 17,
SENSES in FISHES. 49
' * . ’ J\
• * ‘ . . »
On the fore part of the great fac, and communicating with it, a much fmaller one e is found, which likewife contains both cretaceous and vifcid watery matter (g). From this fmall fac a dud e is fent off, which opens into a du &J common to an anterior and exterior horizontal femicircular canal g h , and the other two ends of thefe femicircular canals join together at i\ and where they meet, they alfo communicate with the end of their common duclj£ Hence the large fac b communicates by the medium of the fmall fac d with the anteiioi and with the horizontal femicircular canals g hi Thefe again communicate with each other, firft by their common du£t f) and in the next place a duel, formed by their common duel f and by the du£l e from the fmall fac, joins at i with the meeting of the other two ends of thefe canals, juft under the end of the meatus auditorius externus, where it opens into the large fac*
The two ends l m of the pofterior femicircular canal join with each other at n • and the upper end / communicates direclly with the large fac at k.
When we review the defeription and figures, it appears, that the canals we have from analogy called femicircular are in the fkate circular; and that the ca¬ vities of all of them communicate, through the two facs defcribed, with the me a-
' , . \ t
tus auditorius externus.
In each of the femicircular canals there is a dilatation or pouch, fhaped like that part of our red veins at which valves are found ; yet there are no valves in
them.
The anterior and [pofterior circular canals tonfift of an upper and under por¬ tion ; between which there is a thin ligament p p which fe^ves as a fupport to
them. ' ■.
The large fac refembles our veftible ; and the fmall fac has fome likenefs to
the tube which in birds feems to fupply the place of the cochlea.
The membrane of the drum and the cavity of the tympanum are wanting % which, as the found is not conveyed by the air, we might a priori have fuppo- fed would be the cafe : and the meatus auditorius externus performs the office of the Euftachian tube ; at leaft fo far as that tube may be fuppofed to ferve the purpofe of difeharging ufelefs or hurtful matter. The circular canals are filled with a vifcid liquor fimilar to that in the large fac. The membrane which compofes them is tranfparent, but thick and pretty tough ; and even when di- ftended, they are fo much fmaller than the canals of cartilage which contain them, that between them and the cartilage there is a vifcid watery liquor con¬ tained in a cellular fubftance ; on the threads of which, veffels both circulating
and abforbent, and nerves, are difperfed (h)*
Thefe facs and circular canals are furnifhed with very large nerves, derived
from nerves which refemble our fifth and feventh pairs (i)«
The anterior and horizontal circular canals are fupplied from the fifth pair $
the facs and pofterior circular canal are fupplied from the fifth and feventh
N pairs
i
* • * t
(^) In Tab. XXXVII. fig. 3. thge facs and the femicircular canals are very accurately delineated ; to which therefore this de¬ feription chiefly refers.
{b) See Tab. XXXVII. fig. 4. ledef. (0 Tab. XXXVII. fig. t. and 4. 27—34. and 35. 3 6* 37.
1
l
\
/
/
5°
BRAIN and ORGANS of the
pairs conjoined. After reaching the facs and canals, and running a little way upon their membranes, they lofe their white colour, become pellucid, and dif- appear.
' ' , ,t ' / ' ' ■ .
t ' ; • •• ** . *
v , • '* . 4 / • , < * ^
§ 5. A Defcription of the Ear of the Squalus Squatina of Linnaus ,
' " i V • ’ • ' / ’ 'l ' ' ,
In the fqualus fquatina, or angel fifh, another of the flat cartilaginous fifties, I have found the ftru&ure of the organ of hearing to agree fo nearly with that of the Ikate, that I think it unneceflary to obferve farther, than that the exter¬ nal meatus auditorii are found at nearly the fame place, to wit, over the upper and pofterior part of the head near its joining with the fpine (i). Within the external orifice there is a winding concha K, from which a fmall cylindrical meatus L leads into a large fac or veftible M, filled with a vifeid watery hu¬ mour and cretaceous foft fubftance ; and with this three circular canals NOP communicate-
:
% 6. A Defcription of the Ear in fome of the long-fhaped Cartilaginous Eifhesy and in the
OJfeous Fifh es, ' '
v 1 ' • • 1 \
At the lower end and pofterior ?part of the fides of the cranium, feparated from the brain by membranes only, we find the organ of hearing fituated in the ofleous fifties, and in fome at leaft of the oblong-ftiaped cartilaginous fifties. I have chiefly examined the cod and the fturgeon. In both, the organ confifts of three femicircular canals, to wit, an anterior and pofterior perpendicular canal, and a middle horizontal one (/).
Each of the perpendicular canals has a dilated portion or bulb at one of its ends, where it joins with the horizontal canal (iw); and in the anterior of thefe in
the cod, a fmall fcabrous calcareous ftone is lodged (//), The anterior end of the horizontal canal is likewife dilated (0).
The fmall upper ends of the anterior and pofterior femicircular canals join together, and form a common canal, which defeends perpendicularly (y>).
The hoiizontal femicircular canal has its large end joined to the bottom of the
anterior canal, and its ftnall end joins with the under end of the pofterior femi¬ circular canal (y).
Thefe common canals open into the under part of the perpendicular canal
* *
and
(<■) See Tab. XXXVIII. FGHHI. (/) Tab. XXXIX. KLMttOP. and Tab. X] M See Tab. XXXIX. fig. 1. and 4. L P. and Tab. XL. fig. 3. and 4. fc D.
(*) See Tab. XXXIX. fig. 1. and 4. L L. and Tab. XL. fcg. 3, and 4. E E.
(/>) See Tab. XXXIX. fig. 1. and 4. K. and Tab. XL. fig. 4. G,
(7) See Tab. XXXIX. fig. 1. and 4. and Tab. XL. fig. 4, ^
• 3. and 4. A B C D E F G. (») Tab. XXXIX. fig. 3.
SENSES in FISHES, &c< $i
and of courfe meet there, and communicate freely with that canal and with each other (r).
We next find a fac of confiderable fize, in which a large fcabrous calcareous {tone is lodged (j). This large ftone, as well as the (mailer in the femicircular canal, feems to be furrounded by a vifeid humour.
A hole or opening in the fore or under part of the common perpendicular canal leads into this fac in the burgeon (7) : but I have not obferved any futh
r - . f i a '
opening in the cod or haddock.
Very large nerves are fixed to the bulbous parts of the femicircular canals 5 and fpreading out on thefe canals, they become fuddenly pellucid (ti).
On the fac which contains the large bone, efpecially of the cod, a confider¬ able jierve is fpread in a mob elegant manner
The femicircular canals and large fac contain, befides the bones, a vifeid humour ; and as the femicircular canals are much fmaller tham the canals of hone or cartilage which contain them, fo we find a quantity alfo of vifeid hu¬ mour between their outer part and the bones or cartilages.
In the cod, haddock, and perhaps the whole genus of gadus, a number of fmall fpheroidal bodies, which I have obferved to form part of their nervous fybem, is to be found in this vifeid humour fupported by fmall fibres of vebels
and of nerves (j).
I have alfo in the cod obferved a bag about the fize of a pea a little farther back than the poberior femicircular canal, filled with vifeid humour, and with a nervous filament from the nerve which fupphes the large fac ) and which I fuppofe to be part of the ear (%).
I have not, however, been able as yet to difeover in thefe fibres any meatuS auditorius externus* , .
(r) See Tab. XXXIX. fig. i. and 4. K. and Tab. XL. fig. 4. G.
(/) See Tab. XXXIX. fig. 1. and 2. Tab. XL. fig. 4. H I. (f) Tab. XL. fig. 4. I.
(a) See Tab. XXXIX. fig. s. and 4. QJt S. (*} Tab. XXXIX. fig; 1. and 4. R R?
(j) See Tab. XXXIX. fig. 1. and 4. T. (-3 Tab. XXXIX. fig. 4. V.
CHAP,
, . ( . • •
i
/
I
EXPERIMENTS on HEARING in WATER.
CHAPTER IX.
• - ,7
Experiments on Hearing in Water.
AFter defcribing the ftru&ure of the ear in fiflies, I {hall give an account of a few experiments I made, in 1780, on hearing in water, that we may be able to judge better of the effect of found upon the ears
I employed two bells, - the found of which I was ufed to ; one of them a fmall tea-table bell ; the other much larger and thicker, fo that the found of it could be very well heard at the diftance of a quarter of a mile.
When thefe were plunged under water and rung, I obferved that the found of them was very fenfibly graver; but ftill the ringing tremor of both was very di- ftinguifhable. On performing an accurate experiment, the tea-table bell was found to found in air the higheft G of a common harpfichord ; but in water it founded a fifth falfe lower, or it founded the C {harp under the G.
I next plunged my head under the water while I rung the bell in the air, and heard the found of it diftin&ly. As the tone of the bell is louder and more acute in the air than in the water, I need fcarcely obferve that its found is bet¬ ter heard when the head of the perfon making the experiment is under the water and the bell above it, than when the bell is rung under the water while the head is above it.
. \ ’ »
I next plunged my whole body with the bells, holding their handles in my
hands, under the water ; and then rung them, and was furprifed with the loud- nefs and diftinctnefs of their founds, and could readily diftinguifh their differ¬ ent tones.
, * •
In like manner, when, plunged under the water, I ftruck two ftones held in my hands againft each other, I was furprifed with the lhock communicated to the ears.
I
. / - v ‘ I
* The ingenious Abbe Nollet has, about forty years ago, publiflied ail account of various experiments he made on this fubjeft : “ Le refultat en a ete, que non feulement le bruit, quoique plus ou moins affoibli, fe tranfmettoit a travers “ 1’eau, mais eilcore 1’efpece de bruit, les tons et les articulations de la voix humaine (a)” And the celebrated Dr B.
franklin mentions, in 1762, as his opinion (*), « That Water will convey found farther and more readily than air ; be-
“ caufe two ftones being ftruck fmartly together under water, the ftroke tnay be heard at a greater diftance by an ear pla- “ ced alfo under water in the fame river than It can be heard through the air. He thinks he has heard it near a mile : “ how much farther it may be heard he knows not ; but fuppofes a great deal farther, becaufe the found did not feem
“ faint, as if at a diftance, like diftant founds through air, but ftnart and ftrcrtig, and as if prefent juft at the K ear (£).” J
(a) See Hift. de PAcad. R. des Sciences 1743, p. 26. et Mem. p. 199. &c.
{b) See Letters, &c. by Dr B. Franklin, L. xliv. dated July 20. ) 762*
0
53
EXPERIMENTS on HEARING in WATER.
I afterwards, by means of a firing tied to the handle of the largefl bell, arid to an inflated bladder, fufpendcd that bell in a very deep pool, fix feet under the furface of the water, and took hold of a cord twelve yards long, which I had before tied to its handle* Lthen plunged under the water and pulled the cord, and found that the found was inftantly conveyed to my ears.
In the laft place, I thought of trying an experiment, to determine whether air or water conveyed found quickeft : but as we have no lake near Edinburgh above eight hundred feet broad, I found it impofiible, independently of the dif¬ ficulty of conftrucling a proper apparatus.* to perform an experiment in a deci- five way. * -\ .
It may however be worth while to mention one trial I made. I charged three Englifh-pint bottles each with about ten ounces of gunpowder. I then inferted a tin-tube four feet in length into each bottle, and prevented the water from getting into the bottle by wrapping a piece of wet bladder around the neck of it and the end of the tube which entered into it, and tying the tube and neck of the bottle to each other.
After filling the tube with gunpowder, I fixed to the top of it a piece of match-paper ; and into the match-paper, juft over the top of the tube, I put two ounces of gunpowder.
I then funk the bottle near the fide of a lake to the depth of about two feet, and went into the water at the greateft diftance poflible, which was about eight hundred feet, and laid myfelf on my back in the water, with my ears under its furface, and nofe and eyes alone above it. The match was then fet fire to by another perfon ; and as it was midnight, I faw the flafh of the gunpowder con¬ tained within the match, and foon after heard the noife of the explofion of the powder within the bottle. But I found it was impoflible m this way to deter¬ mine the velocity of the found, with accuracy ; for the gunpowder within the bottle was not fet fire to through the tube fo inftantaneoufly as I had ex-
and third
bottles took fire, I plunged myfelf entirely under water*
Upon the whole.* befides not being provided with a proper apparatus, and not having accefs to a piece of water of fufficient extent, this experiment was not repeated often enough : So that all the conclufion I could draw was, that af¬ ter the bottle burft, I heard one, but did not hear two explofions ; fo that the water feemed to convey the found in nearly the fame time as the atmo-
fphere *.
. ' - . a ,
* A good method of making fuch an experiment would be, to fufpend under water, in a broad lake, a very large and loud-founding bell, fuch as is ufed in churh-fteeples, and for one perfon to {trike this with an iron-hammer, between the handle of which and the trigger of a mulket, or cannon fitted with a lock, a rope was ftretched ; while another perfon was ftationed at the diftance of a mile or more, with one or both ears under the water.
By this means, as two very different fbunds would be produced at tbe fame inftant, the one in air and the other in water, it might be obferved which of them ftruck the ear fooneft. Befides this, the flalh {bowing the exa£t time at which the bell was ftruck, the velocity of the found in the water might be accurately determined.
fJ - ’* N # * v ' ,
O CHAP,
pe6led.
When the powder contained within the match-paper of the fecond
54
The COMMUNICATION of SOUND
CHAPTER X.
Of the feveral Ways in which the Tremor of Sonorous Bodies is communicated, in the different Classes of Ani-
i ,
mals, to the Nerves fpread out on the Bottom of the Ear.
HAving defcribed the ftru&ure of the ear in the amphibious animals and in fifhes, and that of the mammalia and birds being fuppofed to be un- derftood, we {hall proceed to confider the way in which the tremor excited by fonorous bodies is communicated in the different claffes of animals to the nerves fpread out on the bottom of the ear.
It is very generally fuppofed, that in the mammalia and in birds, befide the impreflion which may be communicated to the nerves of the ear by the tremor of the whole bones of the head *, a diflind; impreflion may be conveyed to them in three different ways.
In the firfl: place, and chiefly, by the chain of bones, cartilages, and ligaments, regulated by their mufcles, which conneds the membrane of the drum to the membrane of the oval hole.
■v » ‘
In the next place, as one fcala, or one half of our cochlea, begins at the membrane of the round hole which is not diredly conneded to the membrane of the drum, and as men and other animals have feemed to diftinguifli founds, with confiderable acutenefs, after the chain of fmall bones was deftroyed by dif- eafe or experiment, there is reafon to believe that we receive a fecond and pretty diftind impreflion by the medium of the air contained in the cavity of the tympanum.
This air is fuppofed to be agitated, and to communicate its tremor in two different ways, to wit, by receiving motion from the membrane of the drum •
* 7
and befides this, by a tremor of the external air communicated to it through the Euftachian tube, which, authors pretend, is admirably fuited to this pur- pofe by its fituation, lhape, and the elaltic materials of which it is compofed. Nay, the generally accurate Valfalva relates a cafe, which has been confidered as an undoubted proof that found is conveyed by this channel.
• Yet
* The found of an ordinary watch Applied to the fore-teeth of the upper jaw is heard diftinaiy j but its found is not fo well perceived on applying it in like manner to the teeth of the under jaw : fo that the tremor teems to be conveyed to the portio mollis, not by tire branches of the fifth pair of nerves, or porrto dura of the feventh pair, as has been fuppofed
but by the bones of the head-
/
I
TO THE NERVES OF THE EAR* jj ■
H >4 , #
Yet the following fimple experiment which I made twenty years ago, is fuf- ficient to convince us that no diflind impreflion is tranfmitted through the Eu¬ flachian tube.
I placed an alarm-clock, which rings very loud, upon one cufhion, and 1 flood upon another. Then having flopped my meatus auditoiii extemi, I fet the clock a-ringing, without being able to hear its found. In like manner, when I held my watch near to the external ear, I heard its found diflindly ; but when I held it within my mouth, between my tongue and the loof of my mouth, without allowing it to touch either, and then flopped my external ears,
I did not hear its flrokes.
The primary ufe, therefore, of the Euflachian tube is to furnifh air to the cavity of the tympanum, through which the tremor of the membrane of the drum may, in the firft place, be communicated to the membrane of the round hole: but, in the next place, as air is conveyed to the cavity of the tympanum in amphibious animals where the round hole arid cochlea aie wanting, we mufl fuppofe that the tremor of the air in the tympanum ferves to influence the foot of the flapes and membrane of the oval hole ; or that two different impreflions
are made on the membrane of the oval hole.
We ought farther to conflder, that in the amphibia the tiemor of the chain of fmall bones will be much lefs interrupted by air than it would have been by
a watery liquor filling the cavity of the tympanum.
From the membranes of the oval and round holes the impreflion of found is
undoubtedly conveyed to the portio mollis by the medium of a watery liquor* which fills the cavities of the veflible, femicircular canals, and cochlea, in all
animals. _ . ■
When we now compare the mammalia and birds with the amphibia and
fifhes, we underhand the reafon of fome principal differences of flrudlure.
The whale, though he feems at firfl fight amphibious, has the fame flrudure of heart and lungs as man ; and is therefore obliged to breathe air frequently and regularly, and to live chiefly upon the furface of the ocean. Hence his ear is calculated to receive found from' the air by an external meatus. '
But in the amphibia, where a part only of the mafs of blood paffes through the lungs, and which therefore poffefs the power of breathing arbitrarily, or of plunging under water, and ceafing from breathing for a length of time f , the ear is conflruded fo as to receive the firfl impreflion either from the air or from the water ; but by means of an Euflachian tube, air is introduced into the ca¬ vity of the tympanum when they breathe ; and through it the impreflion is con¬ veyed from the atmofphere, to which their ears are generally expofed, to the bottom of the ear with more force than it would have been by the medium of a
i
watery fluid fecreted into the cavity of the tympanum.
In fiflies, living in and breathing in water, hot only the impreflion of found on the furface of the ear is tranfmitted by the water, but is of neceflity conveyed
, ' • by
/ N 1
f I have obferved a turtle keep under water for three quarters of an hour ; and I have found that it requires five or fix hours to drown a frog,
)
56 The COMMUNICATION of SOUND, &c-
by the fame medium to the bottom of the ear. Hence it is evident they have no occaiion for a cavity of the tympanum nor for an Euftachian tube.
At the bottom of the ear we find in all fillies femicircular canals, fimilar in fhape and fituation to thofe found in the mammalia, but much larger and more extenfive in their furface ; in order, perhaps, to compenfate for the lefs forcible impreffion made by the water in them than in us by the air.
Connected with the femicircular canals, we find facs containing cretaceous matter, which perhaps we may think have as much refemblance to the cochlea as to the veftible in our ear, if we relied that in birds the place of the cochlea is fupplied by a lliort ftreight tube.
The cretaceous matter, which in the pifees of Linnaeus, and fome of his llantes pinnati, forms hard and rugged Hones, may ferve, like the fmall hard bones of our ear, to convey a more forcible impreffion to the nerves fpread out on the membranes which contain them.
Several of the cartilaginous fifhes, the raja, fqualus, &c. have a meatus auditorius exterftus, through which the found is conveyed by a watery vifeid liquor to the inner fides of the membranes of the femicircular canals and fac or facs containing the cretaceous matter : but in the pifees of Linnaeus, and in fome of his nantes pinnati,* as the fturgeon, I have not yet found a meatus auditorius externus ; and as I farther obferve, that the common canal or ve- flible, where the three femicircular canals communicate, is feparated from the cavity of the cranium by a thin membrane only *, and that this cavity, in by far the greater number of filhes, contains a watery liquor in confiderable quantity ; and that, from the thinnefs of the cranium, the tremor excited by a fonorous body may be as readily tranfmitted through their cranium to the water within it, and fo to the ear, as through the temple of the turtle to his ear ; I am more inclined to fuppofe, that in them there is no meatus auditorius externus, than that, from the want of fufficiently accurate inveftigation, it has not as yet been difeovered.
, .
CHAP.
\
.
Of the EYES ik FISHESi $7
CHAPTER XL
Of the Eyes in Fishes.
'
' ■ i . * . '* '
• * , f- . v , V ' * *
' ,v v. . - - i - " v * ! . v - * - “ ,
V • + '
1 ' • *
\ * .1 '
IN treating this fubjccl, I lhall firft make fome curfory obfervations on the
coats, and afterwards confider the humours of the eye, their texture, fpe-
' ' >
cific weight, fhape, and powers of refraction.
In fifties, birds, and in all animals in which objects often imprefs one eye folely or chiefly, the optic nerve is, as a priori we might have fuppofed, much more eccentrick than in man.
I have in a former work obferved (a), that the retina terminates in man near to the roots of the ciliary precedes ; which circumftance is equally obfervable in fifties.
In all fifties, fo far as I have obferved, the pigment on the inner fide of the choroid coat is, as in land-animals which feek their food in the night-time, of a bright colour at the bottom of the eye ; perhaps becaufe the light ftrikes the bottom of their eye with lefs force than in the land-animals, many of its rays being intercepted by the water. To account, however, for the diverfity of the colour of this pigment, or tapetum as it has been called, in the diffeient genera of animals, feems to be a matter of much difficulty. Nay, it may be a que- ftion, whether the chief ufes of the choroid coat in any animal have been clearly afeertained ; or whether we certainly know in what manner the choroid coat is * fubfervient to the retina. Perhaps attention to the powers of the eye in two animals which are mere varieties of the fame fpecies, may ferve to throw far¬ ther light on this curious fubjccl ; I mean the brown and the white rabbit : for in the former, the choroid is every where covered with a dark pigment ; whereas in the latter, although the choroid coat is as much compofed of veflels as in other animals, I have found that the black paint, tapetum, or inner layer of the choroid, is altogether wanting : And hence the colour of the red blood cir¬ culating in the veflels of the choroid is feen when we look into the eye, or makes
their eyes appear red f.
P The
0, ^ %
(a) On the Nervous Syftem, chap, xxt.
f hi juftice to an ingenious and diligent ftudent of phyfic, Mr William Refs, I think it proper to obfervej that I was led to examine this curious circumftance by a letter I received from him in fpring 1781 ; in which he alledged that the choroid coat was altogether wanting in the white rabbit. In a fecond letter, above fix months theieafter, he retraced as an error what he had wrote to me. In the mean time I had found, that although they have the choroid coat, the pigment is wanting. It would be worth while to examine the choroid coat in the mixed breed between the brown and white
rabbit.
/
5»
Of the E V E S in FISHES.
The iris, though not the continuation of the choroid coat, refembles it ni being covered on its inner or back part by a dark pigment; but it has the addi¬ tion of a coloured matter laid over its fore part ; and thefe concealing its veflels and their contents in a living animal, feveral eminent authors, whom Dr Haller follows, have entertained the erroneous idea, that the arteries of the iris in man and quadrupeds do not in life convey the red part of the blood, but the lymph alone; and that they are colourlefs or lymphatic Yet thofe very authors
admit, that the arteries of the iris may be filled with an injection coloured with the powder of vermilion ; and Dr Haller in particular has delineated the large branches of thofe arteries in a very juft and elegant manner as they appear to
the naked eye (V). By what power or mechanifm, then, could he, Mr Ferrein, and others, conceive the red blood to be excluded in life ?
1 he plain facts here are, as I have repeatedly obferved, i \fi9 That by a lkilful
injection the whole iris, to the very edge of the pupil, may be made nearly as
led as a piece of fcarlet cloth, idly , That the whole courfe of the blood, from
the trunk of the ocular artery to the arteries of the iris, may be traced with the
naked eye. ylly, That if any part of the iris be cut or pnndured in a man,
which I have feen happen in the attempt of extracting the cryftalline lens, red
blood immediately flows from its veffels. Nay, in one fuch cafe, a red-
coloured fungus, rooted in the iris, afterwards puflied out at the wound in the cornea.
In one kind of fi(h, the fkate, the upper part of the iris in the horizontal
LfjaT fas 7 Pal"ated Pr“rf! « = '*hi'h probable the
hght , and perhaps he lets fall this curtain i„ dlM „f fl * „ £
worth while to obferve, whether the mind of ,h. animal, independent of the
o' bText IT f“h * T„“ °V'r * “ 1 ha™ '°" V obferved
to be exercifed by the parrot; which, in an obfeure light, opens and lh„r, ,l,»
pupil alternately when agitated by pallion. P “ B h
Inman the cornea is, beyond doubt, covered with the continuation of the lt.» ; which in the found Hate polfelfe a conlid.rable degree of fenlibility and when irritated by extraneous fubllance, flicking in it, occaftons, as , hJ’ ^ ral times fan violent inflammation of the whole eye ; in co„fe,„e„ce of .S fpecks, full of veflels containing red blood, are often produced upon the cornea’ and, what „ remarkable, and ufefnl be attended to by the oculifl thefe vtf feh from whatever caufe produced, are, fo fa, as 1 have obfe„ed, ’no, the I„ g.n.1 veflels of the cornea running between its layers, dilated by the inflam tion, but are new velfels growing f,„„ ,he veflels of the tunica Id' s tended over the external furface of th. cornea. Hence we perceive he „ “ of attempting to remove thefe by operation and external ap^cation^P’""7
- 1 • The
(t) Ruyfch; V.eulTens, Fcrrcm, Mem. de l’Ac. lyjp. Haller, Phyf. t. v. p.
(c) Haller, Fafcicul VII. Tab. VI. fig. 4. 5. 6. *
(e) Dr Haller, El. Phyf. L. xvi.. p. 362. unjuftljr denies the fenfibilitvr of tl ^ ^ ^ VIL **' 3' 22‘
“ &C- 7 °f the ! “ %na aut homo edit, Mt
/
Of the EYES in FISHES. Jf$
V • , *
The inner part of the cornea feems to be lined with a thin very denfe mem¬ brane, fit for confining the aqueous humour. But in man and quadrupeds it is very difficult to feparate thefe coats of the cornea from each other; whereas in fiflies they may be feparated with the utmofl eafe.
The humours of the eyes of fiflies are proportionally in greater quantity, of much larger, than thofe of animals living in air. Thus the eye of the cod is very nearly of the fame weight and depth, and its axis of the fame length as the eye of the ox. On this account I have, in the following experiments* made chiefly the comparifon of thofe with each other.
As the rays of light fuffer great refra&ion in palling from the rare medium of air into water, the cornea of land-animals is very convex. From this they pof- fefs alfo two other advantages ; that a fmall motion of their iris excludes the fuperfluous quantity of light ; and that their cryflalline lens needs not be very convex, and may therefore be placed at a diftance from danger.
But as there is little or perhaps no refra&ion of the light palling from falt- water into the aqueous humour of the eyes of fiflies, their cornea has little con¬ vexity, and perhaps would have been altogether flat, but that a quantity of aqueous humour is neceftary for giving room and protection to their very con¬ vex cryflalline lens, and for allowing the motion of the iris. Nay, in one ani¬ mal, which makes the neareft approach to this clafs of animals, the fepia loligo, I have found the cryflalline lens attached to the cornea, and the aqueous hu¬ mour and iris altogether wanting (g).
The cryflalline lens is known to be compofed of concentric layers, and thefe of fibres; and the central part being harder than the furface of the lens, has been called its nucleus. But it may be obferved, that the hardnefs does not increafe from the furface to the centre in a perfectly equable manner ; but that, at the depth of one third nearly of the diftance of the furface from the centre* there is a fudden increafe of the hardnefs of the lens : So that if the capfule of the lens be feparated from a number of lenfes of the fame kind of animal, and the lenfes rolled between the thumb- and fingers in a bafon-full of water, with the view of detaching the foft fuperficial parts, the nuclei of all the lenfes will remain nearly of one fize ; and their diameter will be to the diameter of the en¬ tire lens nearly as two to three*
After repeatedly comparing together the fpecific gravity of the aqueous, the cryflalline, and vitreous humours of the ox and cod, by weighing them in air and water, I found their proportional weight to be as follows ;
9 ' < I ,
Parts.
Spring-water, . * . . . 1000
Aqueous humour, * , • * * 1000
The vitreous humour of the ox, . - * i o 1 6
The vitreous humour of the cod, . . * 1 ° 1 3
The
( /) Dr Porterfield, and others, miftake in fuppofing the eyes of fifties to be flatter behind, as well as before, than the eyes of land-animals. — Porterfield, v. ii. p. 262.
(g) See Tab. XL1. fig. 3. A «<. 1 '
I
\
1
6o
Of the EYES in FISHES.
The whole cryftalline lens of the ox,
The whole cryftalline lens of the cod,
The outer part of the cryftalline lens of the ox. The outer part of the cryftalline lens of the cod, The nucleus of the cryftalline lens of the ox. The nucleus of the cryftalline lens of the cod,
Parte.
IIO4 H65 *1070 I I40 Il6o 1200
On comparing the cryftalline lens of the ox with that of the cod, I found that they were very nearly of the fhape delineated in Table XL*, fig. 1. where the outermoft dotted lines reprefent an horizontal fection of the lens of the ox, and the continued lines the fame of the cod : and they meafured one-fourth part of the diameter reprefented ; or one-tenth of an inch in this figure reprefents one-fortieth of an inch in their cryftallines : Or I found the radii of the fpheres which compofe the lens in thefe two animals to be in fortieths of an inch nearly as in the following table.
' ' ; -v •"». * ■ ' / v
I •
, p ./ ,
The radius of the anterior part of the lens of the ox, . . 21
The radius of the anterior part of the lens of the cod, . . 14
The radius of the pofterior part of the lens of the ox, . . 15
The radius of the pofterior part of the cod, which is nearly an hemifpheref, 1 34J
/ v ' . 1 , .
In the laft place, I found that the focus of the rays of the fun, which was
nearly ^th part of an inch in diameter, was diftant from their pofterior part,
In the ox, ~ of an inch ;
But in the cod, not more than
s 40
And I obferved that the diftance of the focus from the furface of the whole lens, or from that of the nucleus in the cod, was nearly the fame.
The focus of the nucleus of the lens of the cod placed in water was about — of an inch diftant from its back part.
Hence it is evident, that the cryftalline lens of the cod, but efpecially its nucleus, is much more denfe, and refra&s light more readily, than that of the ox: nay, that its refradfion, inftead of bearing proportion merely to its fpecific weight, with fome little addition on account of its containing inflammable
matter, which is the common fuppofition f, is more powerful than that of
' • • * - .
common
t The celebrated Dr Petit Has, in the Mem. de l'Acad. 1730, p. p. defcribed the breadth and thicknefs of the crvftal- hne lens parttcularly of the ox, and the radii of the fpheres which compofe it, with fo much appearance of accuracv that his defcr.pt.ons have been univerfally received by authors : Yet I have not only obferved by meafuring that the len's f the ox is much more convex on both f.des than he reprefents it; but i, will be found impoff.ble, with fu’ch radii to A cr.be a lens of the breadth and thicknefs he himfelf afligns to it. When we aflume his radii and breadth, a much flatter lens than that of the ox ,s produced . and which the innermoft dotted lines Id L m reprefent in Tab. XL * fi
Nay, it is demountable, that he has erred greatly in every example in his Table of the human lens, as well as' in that of “* h'S rad“ Mt inltance, with the breadth and thicknefs of the lens he found by
, t Dr Porterfield, V. i. p. 232. 5 9. p. 2-8. &c. Pemberton. Haller, El. Ph. 1. 16 n M • ■ , , ,. .
rcfradtilem . Parvam elfe qua aquam fuperat prarogativam nuperi fatentur. * q“* V‘ " “ * “
I
Of the EYES in FISHES.
6 i
common glafs : for the nucleus of the lens of the cod, which is nearly fpherical, forms its focus at the diftance of a little more than one-iixth part of its diameter; whereas parallel rays of light, palling from air through a fphere of glafs, are not collected into a focus till they are one-fourth of its diameter diftant from its pofterior part.
The lateft and molt eminent writers on the eye have taught, that a principal ufe of the fpherical figure of the cryftalline humour of fillies, is to enable it to collect the rays of light more powerfully, or nearer to the fore part of the eye, than could be done by a lens compofed of two fmall portions of a fphere j\
But on calling the eye on Table XL*, fig. 2. it appears, that the focus of a fphere is nearly, but not exactly, for the proportion varies according to the me¬ dium, as much more dillant from its anterior part, than the focus of a lens compofed of two portions of the fame fphere, by as much as the thicknefs or diameter of the fphere is longer than the thicknefs or axis of the lens.
Nay, from the fame figure it is evident, that a lens, the axis or thicknefs of which is equal to the radius, and its breadth equal to the diameter of the fphere, and compofed therefore of two portions of a larger fphere, has its focus confi- derably nearer to its fore part than the fphere has.
Upon the whole, therefore, we are led to the conclufion, That the primary ufe of the almoll completely fpherical figure of the cryftalline lens of fillies, or great convexity efpecially of the anterior part of their lens, which I find pro¬ jects in the cod about feven fortieths of an inch beyond the iris, is to take in a large field of the objeCts around them ; which was particularly neceftary, as the motion of their neck is inconfiderable.
To enable them, with the fame length of the axis of the eye as in the qua¬ druped, to colled: into a focus on the retina the rays of light coming from the denfe medium of water, four chief circumftances concur.
In the firft place, We obferve that their cryftalline lens is more convex, or compofed of portions of fmaller fpheres, than in land-animals.
In the next place, We have found that their cryftalline lens is, in correfpond- ing parts, much more denfe than in animals which live in air.
Thirdly, That the lens in fifties pofteftes powers of refracting light far be^ yond what have been calculated by authors, who have proceeded on the fup- pofition that thefe powers were proportioned nearly to its fpecific gravity.
In the laft place, The vitreous humour of fillies being lighter than that of land- animals, the rays of light iftuing from their lens will be refraCted in a greater degree, or brought fooner to a focus p
Q. 1
» 1 ' % #
f Dr Porterfield on the Eyes, v. ii. p. 261, 262. Dr Haller, El. Phyf. L. xvi. p. 468. Hinc pifeibus, quorum radii mi¬ nus refringuntur, lens pene fpluerica.
r x
$ Dr Haller, on this fubjeft, Pr. Lin. Phyf. DXXXVIlI. and in Elem. Phyf. t. v. p. 467. commits the overfight of fuppofing, that becaufe the vitreous humour is more rare than the cryftalline lens, it will have the effeft of making the rays longer of coming to a focus ; whereas the lefs its denfity is fuppofed in proportion to that of the lens, the more the rays will be refracted and the diftance of the focus leflened. Hence the vitreous humour is made viftid and heavy, merely becaufe a culhion for fupporting the lens at a proper diftance from ths retina was neceftary.
/
Of the EYES in FISHES.
I cannot conclude without obferving the probability, that attention to the denlity, lhape, refracting powers, and connection of the humours of the eyes of animals, may lead to the Hill farther improvement of optical inftruments.
CHAPTER XII.
Anatomy of the Sepia Loligo.
^ i
rT",0 this account of the ftru&ure of fifties, I fliall fubjoin a defcription of JL that of the Sepia Loligo ; which I have found not lefs remarkable in its internal ftru&ure than in its external ftiape. By mod: authors it has been ranked among the fifhes ; by Linnaeus it has been placed among the worms ; but per¬ haps it may moft juftly be confidered as a link connecting thefe two clafles of animals.
The fepia loligo, which wants fins, has a triangular-fliaped tail (fee Tab. XLI. fig. i . A A), and a hollow conical-lhaped mufcular {heath, which inclofes its thoracic and abdominal vifcera ; reaching from its throat, where it is open and admits the fea- water freely, to its tail, where it is fliut. This {heath cut open is reprefented at B B.
* i •
Near the mouth of the great {heath there is another flelhy conical funnel C, wide behind and narrow before.
The fepia I laft difte&ed had ten arms D D D, &c. with a great number of cups E E E on each ; by means of which it fixes itfelf to a rock ; and with a beak F, like that of a parrot, it breaks the fhells of the fea-worms on which it feeds.
From the mouth the cefophagus GG fig. 3. runs ftraight down, covered be¬ hind by its principal bone, or os fepise, to end in a very mufcular ftomach H, fig. 1. fituated near the tail.
From the fore part of the ftomach, very near its cardia, the inteftinal canal I begins ; and after making a very few turns, ends in the re&um KK, which runs ftraight upwards on the fore part of the liver, and opens about the root of the flefliy funnel C.
The liver M M is of great fize, and is fituated lengthwife on the fore fide of the oefophagus.
On the fore fide of the liver, between it and the reCtum, the ink-bag N is fituated, tied to both. This bag is of a conical ftiape, and of confiderable fize.
The
ANATOMY of the SEPIA LOLIGO*
The duel from it, O, runs upwards between the liver and re£lum, parallel with the redum; into which, very near the anus, it difeharges itfelf.
As I did not obferve any other bladder connedled with the liver, I fuppofe that the ink is the gall of this animal ; yet while I was detaching the ink-bag and its dud from the liver, I did not obferve that any gall-duds were cut, nor could I perceive, on fqueezing the liver or ink-bag, that any gall or ink was ef- fufed. Still, however, confidering the fituation and connedion of the ink-bag, this is perhaps not an improbable conjecture. If fo, we are led a hep farther ; I mean, that as in this animal the bile does not ferve any of the purpofes com¬ monly afligned to it, but is thrown out merely to affift the animal in making its elcape, there is fome reafon to fufped, that one principal ufe of the liver may be to drain off from the conhitution fome matter that is hurtful to it, or that the bile is an excrementitious liquor.
Notwithhanding the great fize of the liver, I did not obferve any organ ana¬ logous to the fpleen.
When we review the parts that have been deferibed, it feems propable that the animal may pufh its body forwards by the motion of its tail. But if the tail is at reft, and the large outer fheath ftrongly and fuddenly contraded, the re¬ action of the water within the fheath will throw the whole body of the animal backwards, whilft, at the fame inftant, the ink will be thrown out of the bag, and perhaps direded and thrown with ftill greater force by the adion of the muf- cular funnel C.
* %
If the tail be direded upwards, it is plain that the animal may, by fuch an
exertion, jump upwards out of the water, and ftill more readily make an efcape from its enemy.
Between the abdominal bowels and the back-bone I obferved a large thin- coated bag P, which in the firft fepia 1 examined was empty, and feemed to re- femble the fwimming-bladder of fifties : but in others I difteded afterward I found it filled with a watery liquor, and a paflage or duel into it from a glandular-looking organ ; from which I fuppofe it to be the bladder of urine {h).
On the under fore part of the liver and ink-bag, I remarked a glandular- looking organ LL, confiding of a number of minute lobes; which I fufpeded to be the ovarium of this animal.
In another larger fepia, I found a confiderable fac, with a large and long dud from it, which terminated near the anus ; and from which, on a flight preflure of the fac, vermiform bodies were difeharged (i). Whether thefe are portions of the organs of generation, which, after fome degree of putrefadion, were de¬ tached in this tender animal by flight preflure ; or whether thefe bodies are na¬ turally difeharged in the produdion of the young, future obfervation mull de- termine.
The gills or lungs of this animal are two conical-lhaped bodies QQ - one • ■ fixed
I
(/,) See Tab. XLII. PQJIS. -
(0 Sec Tab. XLII. M N 0, and two figure* at the fide of the Table.
64 ANATOMY of the SEPIA L O L I G O.
%
fixed on each fide to the inner part of the loofe mufcular {heath, between it and the abdominal bowels.
Each of thefe gills is provided with a heart for driving the blood through it ; in confequence, perhaps', of the difiance from each other at which the gills are placed. Another Angularity occurs, that the branchial or pulmonary veins, or veins returning the blood from the gills, infiead of joining together to form the aorta, as in fiflies, run into different fides of a mufcular fac or ventricle, fhaped like an egg ; from the two ends of which the aortae are fent out.
Hence there are in this animal three hearts or organs for reftoring momentum to the blood : of which, with their veffels, I {hall now give a more particular defeription, beginning with the venae cavae.
The anterior vena cava (/£), R, is placed under the liver, contiguous to the re6lum; and receives branches from the arms and the head S, the liver T, the ovarium, the fiomach, inteftines, and from fome fhare of the upper and back part of the body VV.
Near to the back part of the liver, the anterior vena cava divides into two equal branches W W, which meet, with two large veins XX from the under and pofierior part of the animal, and which are analogous to the pofterior venae cavae of fiflies. The cavae, where they meet, have a degree of reticular work, or corneae columnae et foveae, on their inner fide ; and from their meeting, facs Y Y, of the fame fize and fliape on right and left fides, are produced ; or on each fide an oblong bag is formed, analogous to our right auricle ; and both bags are in- clofed in one large membranous fac or pericardium. To each of the auricles a ventricle ZZ is connected, of the ordinary conical fhape, and inclofed in its proper membranous bag or pericardium.
From each ventricle an artery aaaa is fent out to the correfponding gill.
When the ventricle of the heart and this artery are cut open, the communica¬ tion between the auricle and ventricle is found to be of a round fliape, fig. 2 .b ; and a rifing flefliy edge e9 on the outer fide of it between it and the artery, feems to ferve the office of a valve.
At the beginning of the artery a three valves d are formed, refembling the valves in fiflies.
The artery of the gill, or pulmonary artery a a, fig. 1. is remarkably large in proportion to its correfponding vein e e .
The pulmonary veins terminate near the middle of a thick flefliy fac g, which produces a conical end both on the fore and back parts, or refembles two cones joined together by their bafes. From the fore end of this conical ventricle a large artery h is produced, which may be called the anterior or afeending aorta.
» » 1
The artery from the back end of the ventricle or pofterior aorta i, is confide* rably fmaller than the anterior.
When this ventricle and thefe two arteries are flit open (fee fig. 2.), a pair of
(*) See Table XLI.
mem-
ANATOMY of the SEPIA LOLIGO.
H
\ 9
membranous valves, like thofe at the termination of our thoracic dudt, are found at the termination of each of the veins of the gills k k.
At the beginning of both aortse there are membranous valves //.
The anterior aorta fupplies the arms, the head, the liver, the mufcles above the back-bone m, the alimentary canal (fee fig. i.^), and the organs of urine and generation.
The pofterior aorta gives fmall branches to the two pulmonary hearts oo, and to the ink-bag^, and then runs towards the tail and under part of thev outer mufcular (heath q, fupported by a double membrane r, which fixes the abdomi¬ nal vifeera to that (heath.
From all the branches of the aorta the blood returns diredtly by the two venae cavse to the pulmonary hearts ; for there is no vena portarum as in fifties.
The eyes (fee fig. 3. 1,1,) are very large, and have broad eye-lids. The vitreous humour has the ufual appearance : but the cryftalline t is inclofed be¬ hind in a fofter fubftance or coat u ; and before is glued by a hard plate to the cornea, without the intervention of the iris or aqueous humour. So that the cryftalline lens confifts of three different parts or pieces.
Between the eyes a foft fubftance is found, which I fuppofe to be the brain v , and which is placed immediately above the oefophagus G G. To it two large lobes x x, fomewhat firmer than the middle part, are clofely connected, whe¬ ther cerebral or mufcular parts I am uncertain ; and from or through them the optic nerves y y run to the bottom of the eye.
The middle part of the brain is conne&ed by crura to two lobes zs, placed lower and farther back, which feem to be analogous to our cerebellum. The left lobe is left bare at s.
From the latter a white thread, larger than a briftle, runs backwards, which has fome diftant refemblance to the fpinal marrow ; but from the fmallnefs of it, there is a difficulty in determining its nature with certainty or much proba¬ bility. v
Near to the fubftance which I fuppofe to be the brain, I found a fmall done which refembles the ftone in the ear of filhes(^) ; but I have not lately met with
one of thefe animals in order to profecute this obfervation.
\ •
(<) Tab. XLII.
R CHAP.
t
66
ANATOMY of
THE
ECHINUS MARINU &
CHAPTER XIII.
* - V
t
*
.. .» ( f
Anatomy of the Echinus Marinus;.
IN treating of the abforbent veffels of the fkate fifh, I obferved that the firft origin, by open mouths, of fome of its cutaneous abforbents, could be de* monftrated by injedting liquors from the trunks into the fmaller branches of certain lymphatic veffels ; and I mentioned abforbent veffels proper to one of the clafs of worms, to wit, the Sea-egg or Echinus efculentus of Linnaeus, G. 299. S. 1. which I had difcovered and read an-account of to the Philofophical Society of this place in Auguft 1761. I lhall therefore add, as an Appendix to this work, the defcription of this very curious animal.
I was led to examine the ftructure of it, by having been appointed by the Philofophical Society of Edinburgh to report to them my opinion of a paper on the fubjedt, which had been prefented to the Society in November 1760 by the late ingenious Dr Thomas Simfon fenior of St Andrew’s.
The Dodtor, in his paper, which was afterwards withdrawn, dwelt chiefly on the want of brain in this animal ; from which he thought additional force was given to the dodrines he had published in his Eflays on the Vital and Involun¬ tary Motions.
I entitled my Paper, Further Observations on the Sea-egg. or Echinus. Since that time, I have traced with greater accuracy fome particulars in the flrudture of its parts ; which, though few in number, are fo lingular and re-
maikable, that the knowledge of them ferves to enlarge our views in interefting points of phyliology.
The fhell of the Echinus is covered with a Ikin, and has many thoufand thorns articulated with it by means of mufcular ligaments (/) : Hence the thorns ferve in place of feet ; and are fo tenacious of their powers, that I have feen
the pieces of a broken fhell walk off in different diredtions. Yet there is no appearance of any organ like to the brain.
It does not, however, follow that they are deftitute of nerves ; fince thefe may exift independent of the brain, and be fo fmall as to efcape obfervation.
In the interflices of the thorns there are three kinds of bodies foft at the ends, fupported on calcareous (talks inclofed in a membrane, and articulated
with
(7) See Tab. XLIII. and Tab, XLIV. fig. 3.
ANATOMY ofr the ECHINUS MARINUS.
6*
with the fliell by means of mufcular membranes. Not only the roots but the points of thefe bodies, which are fhorter than the thorns, arc in continual mo¬ tion, poffefling the powers of opening and fhutting like the fingers of our hand, and having thefe points fupported by a mixture of cretaceous particles with mufcular fubftance (/;/).
Thefe bodies fomewhat refemble the antennae of infects, and probably fupply the place of the organs of the fenfes in the more perfect animals.
The mouth is furnifhed with five teeth, with large fockets (/z), which are tied to the fliell by a very ftrong membrane ; around which there is placed, on the inner fide of the fliell, an irregular ftrong circle of cretaceous matter, from which a pair of mufcles is extended to each tooth, and other mufcles join the fockets of the teeth to each other ( o ).
The cefophagus (/>), after running about three inches in length, and being tied by a ligament to the fide of the anus, makes a turn, and foon opens into a wider canal or intefline, nearly in the way our ilium opens into the fide of the colon; and this intefline, after deferibing two waving circles around the fliell, defeends to the anus (^).
On the under edge, of the whole length of the mefentery, I found two vef- fels without valves, nearly equal in fize and parallel to each other, which I in- jedfed with quickfilver (r) ; and from them filled a beautiful net-work of veffels, not only on the inteflines (j-), but difperfed on fine membranes, which tie the intefline to the inner fide of the fliell.
I could not, however, obferve that thefe two veffels communicated with each other diredlly, nor by the medium of any organ like to our heart ; nor could I obferve in the living animal any beating organ like to the heart : yet near to the anus, and connedled to the redlum, which is the place of the heart in many other worms, I found a fmall organ W* Tab. XLIII. fig. 2. which feems to be hollow*
. ; . ,■ . • . /
It appears highly probable, that one of thefe - veffels is the principal artery or aorta, and the othei analogous to our vena cava ; and that they communicate by invifible branches, and circulate the blood by the mufcular action of their coats, without the intervention of a heart, nearly in the way the veffels in fillies carry the blood from the gills back to their heart.
In what manner the chylous or ladteal veins communicate with thefe two veffels, I have not yet been able to difeover.
In fome animals, as in the human taenia, or fafciola hepatica in fheep, the cefophagus, I have obferved, may be confidered as the aorta, conveying the
chyle or bile directly to all the parts of their bodies : but here it is probable the
# » . 1
ladteals
{m) Tab. XLIV. fig. 18. 19. 20. 2i, , (*) See Tab. XLIV. fig; 3. fig. 16. 17.
(*) See Tab. XLIII. fig. 1. D. E. Tab. XLIV. fig. 13. i7.
(?) See Tab. XLIII. FGHIKLMNOP Q_, and Tab. XLIV. GKLQ_.
(r) See Tab, XLIII. fig. 1. KLMNOPQ^.
(p) Tab. XLIV. fig. i7.
(/) Tab. XLIII. M.
\
I
68
* »
ANATOMY of the ECHINUS MARINUS.
lafteals pour the chyle into that veflel in the meferitery which is the largeft, and refembles our vena cava.
A large roe, which almoft furrounds the rectum, and is divided into five lobes, difcharges itfelf by as many ducfts, which pierce the {hell near to the anus, after communicating with each other (/).
The roe, with the inteftinal tube, are the chief parts which prefent within the (hell ; and to which that part of the ftru&ure, which is by far the moft in- terefting to the phyfiologift, and which I am about to defcribe, may be confi- dered as fubfervient.
Between the inner fide of the {hell and the parts I have been defcribing, to wit, the inteftinal tube and the roe, a large quantity of a watery liquor is lod¬ ged, which taftes like fea-water, and contains a thirty-fecond part of its weight of faline matter ; which, chemically examined, was found to confift chiefly of common or fea fait, but with all the other principles which fea-water contains.
This watery liquor is fecreted from the fea-water by means of the following very beautiful ftrudture.
The fhell of the echinus is pierced with upwards of four thoufand holes, dif-
pofed in five pairs of rows or phalanges, which extend from near the outer fides
of the teeth to near the anus.
! > 1
The holes are difpofed on the outer fide of the fhell in pairs (//) ; and with each pair an abforbent veflel correfponds (*).
This abforbent veflel, in its collapfed ftate after the death of the animal, is upwards of half an inch in length. Its end is covered by a flat plate ; in the middle of which is a hole, vifible to the naked eye, being about one hundred and twentieth part of an inch in diameter, and very like one of our pundla la- chrymalia.
From the outer edge of this plate a number of teeth proje£l, like the teeth on the wheel of a watch.
The flat plate is very tough ; contains fome cretaceous particles ; and, when prefled between the fore teeth, feels almoft like a plate of talc. It feems to confift of a number of pieces joined together ; which are broader near its outer
edge than at the hole in its centre (j).
\
The dud from this plate to the Ihell is compofed of pale-coloured circular or tranfverfe fibres in fafciculi or bundles (j) ; and two fmall bands of fuch pale- coloured longitudinal fibres are obfervable on oppofite fides of the tube (z) : or its ftru&ure refembles our colon with the mufcular bands called its liga¬ ments.
Thefe fibres, which have the appearance and the action, as we {hall find, of mufcular fibres, are lined with a membrane.
When we trace the two holes which pierce the {hell, we find they diverge
(0 See Tab. XLIII. fig. 2. X Y Z.
(u) Tab. XLIV. fig. i. 2.
( >)) See Tab. XLIV. fig. 6. 7. 8.
to
r f m
(x) See Tab. XLIV. fig. 3. and (z) Tab. XLIV. fig. 11, and 12.
\
ANATOMY of t he ECHINUS MARINUS. 6$
to oppofite fides of the row or phalanx of holes (a), and lead to leaves of doubled membranes, not unlike the procedes or fubdivifions of the gills of a Ikate (Jb).
When I injected quickfilver into the mouths of the external abforbent vedels, I found that it filled and diftended completely the internal leaves or doubled membranes (c).
When, after this injection, I applied a common magnifying glafs, I could diftindtly obferve the dudts by which the quickfilver entered the doubled mem¬ brane : nay, I could trace a plexus of communicating branches formed upon it* furrounded by a circular vefifel, from which the quickfilver was conveyed by a fingle tube into a large pipe, nearly one-twentieth part of an inch in diameter ; and which ferves as a trunk, receiving the fluid from one of the pairs of rows or phalanges ( ct).
Each leaf or doubled membrane receives at lead: two branches from different external abforbents. Hence we fee the reafon why each external abforbent db vides into two diverging branches ; that although an accident fhould dedroy one of the external tubes, the internal membrane may not be without its fupply of liquor.
The trunk lad defcribed, and there are five fuch (/), divides into two branch¬ es, which terminate in large facs or receptacles (f), over the fockets of the teeth, communicating with each other : and from thefe the liquor pades down the fockets of the teeth, and is difcharged into the fea, on each fide of the tooth, between the focket of the tooth and beginning of the cefophagus
The external abforbent vedel has not only the appearance of being mufcular, but contra&s fuddenly when touched with fea-falt; and, like an earth-worm, or the probofcis of an elephant, it podedes motion in all diredtions {h) ; and particularly the animal podedes the power of dretching it to the length of an Inch and a half, and upwards.
' When it is elongated, it becomes much finialler ; and the plate at its end, which, as I have obferved, appears fiat after death, is pufiied out into a conical form, and the hole in its centre becomes much fmaller (/)»
The internal double membrane, with its vafcular plexus, is likewife evidently mufcular, altering its fhape and fituation when it is touched rudely with a knife or probe, or when fea-falt is fprinkled on it.
There are no valves within thefe vedels: for, from the internal trunks, the plexus upon the doubled membranes, and the external abforbents, may be filled with injection ; or when, after death, the teeth with their fockets are preded inwards, the watery liquor contained in the internal du&s pades outwards through the {hell, and fills the external vedels.
- . . . S No
(a) See Tab. XLIV. fig. i. 2. 5.
(c) See Tab. XLIV. fig. 13. D E.
(«?) See Tab. XLIII. fig. 1. and 2. R S T U V.
1
(^) See Tab. XLIV. fig. 17. E E.
(/) See Tab. XLIV. fig. 1 r. and 12.
(b) Tab. XLIV. fig. 13. D E.
(d) Tab. XL IV.fig. 13. D E F, fig. t4. fig. 1 5, (/) Tab. XLIV. GGGG.
(b) Tab. XLIV. fig. 9. io. 1 i< 12 „
I
I
ANATOMY of the ECHINUS MAR IN US.
No communication of the internal dudls and plexus with the cavity within the fhell is difcoverable by the injection of quickfilver.
On reviewing the ftrudturc of thefe ducts, there can be no doubt that the fea-watcr is abforbed by the external open-mouthed vefTels, and conveyed from them through the fhell into the plexus of the internal doubled membranes : from which a fecretion of part of it is made by invilible velTels into the cavity of the fhell, while the remainder of the fea-water pafles from thefe plexus into the five large internal duels ; and .from them through the receptacles at the roots of the fockets of the teeth, to be difeharged into the fea by ten apertures at the fides of the teeth.
We mud likewife fuppofe that there is a conftant change of the water within the fhell ; and that there are therefore abforbing vefTels which correfpond with the fecerning. Thefe are invifible ; and whether they terminate in the plexus and five