38 D I S C O V E R Y OF THE L A C T E A L
which in this animal are, in common with the reft of the fyftem, large, and readily
appear on opening the abdomen.
Further, the fpleen is in fiihes as remarkably dark coloured as in man, and, in
proportion to the reft of the body, as large; nay, in the fqualus fquatina, or angel
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 tliere is much more
rednefs in the flefli^ and many more red particles in the blood, than in the cod
or ikate, 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.
Fa£ts which fuit ill with the theory propofed.
Upon tKe whole, therefore, Mr Hewfon appears to have left this part of phyiiology
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 fuppofmg that one ufe of the fpleen
had been, as he contended, to complete the red particles of the blood; ftill, as
its venous blood pafted not into the vena cava, but into the 'vena portarum and
liver, wliich we cannot fuppofe to happen in vain, it would have followed, that
the fpleen was alfo fubfervient to the liver, althcuigh we ihould not have been
able to fpecify the particular nature of the fervice it performed.
C H A P T E R VI I .
O f the.iirit Disxiozfi^ of the SY S T EM of LA C T E A L and
LYMPHATIC VE S S E L S of FRSHEE, BIRDS, and AMPHIBIOUS
ANIMALS.
I SHALL take this opportunity of eftabliihing, in a few words, my claim to the
firft difcovery of the exiftence of the ladeal and lymphatic fyftem in birds
and amphibious animals, as well as in fifhes, in oppofition to the pretenfions of
the late Mr Hewfon.
In a paper I publiftied in 1770 (j), I proved, " That in 1758, I obferved a
" veifel in the mefentery of the common cock, which I fufpecled to be the
" trunk receiving the ladleal veiTels.
" In April 1759, when treating in my Courfe of Ledlures of Comparative
" Anatomy, I obferved in a cock what looked like la£leal veflels collapfed, and
" of a bluifli. colour, which feemed to terminate at the back-bone between the
" tefticles."
I
0) Stale of faas conwrning tin pjracenlc/ls of the thorax on account of air effuftJ, and lympliatic vcl&ls in oviparous animals.
AND L Y M P H A T I C VESSEL}
39
I not'only mentioned but ihowed tliefe publicly to the iiudents of anatomy;
and I at the fame time faid, that Dr Cullen had lately told me that Mr John
Hunter had feen lymphatic veflels on the neck of a fwan: And from the two
obfervations conjoined, £ concluded tliat fowls had ladeal and lymphatic veiTels
like our own.
" Next winter, on April 23d 1760, I difcovered lymphatic glands on the
" neck, blew them up, and valvular lymphatics from them, terminating in the
" ends of the jugular veins."
After fliowing thefc pubhcly to the Undents, t repeated what I had mentioned
the preceding winter, but now fpoke with greater firmnefs concerning
their lafteal vcfliils, as I always confidered the lafteal and lymphatic veffels as
different branches of the fame general fyftem. Thus in 1757, I had treated of
both under the name of Vena; Lymphaticae Valvulofie (i).
The following day, to wit, April 24th 1760, " I difcovered a whole fyftem of
" lafteal and lymphatic veflTels in a ikate fifli, running towards the heai"t 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 diiTecTiing 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 inteftines by a
hole I cut in them, without obferving that thofe coloured fubftances entered
their ladeal veft:els.
In the fame fummer I repeated my obfervation of the lymphatic veiTels and
glands in the neck, and noted their appearance as follows.
" In the neck, I obferve very diftinftly lymphatics, which pnfs throug-h fevc-
" ral glands like to our glandulze concat-'nai^«:. 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 iilled with the air (K),"
In fummer 1765, I difcovered lacteal veflels 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 tliis preparation, which I ftill preferve, publicly the following
winter; and a di-awing of it was then made by Dr Palmer, now phyftcian at Peterborough
in England. An engraving from this drawing was pubHlhed in my
ftate of faffcs, and is republiflied in this work (x).
From 1759 to the prefent year, it has been my pradice, in my courfe of
ieilures, firft to defcribe what I had obferved refpe£ting the ladeal and lymphatic
veflels in thofe animals ; and then to point out in the mefentery of the common
cock the ladeal veiTels, and in the neck the lymphatic veiTels and the
glands
(0 Dc Venis Lyiri:U
(x) Sec Tab. XXX.
{») Nest winter Mr HcwfoD attended my courfc of leflures.