MR RI EH Y. 
require a particular defcription ; we need only obferve, 
therefore, that the bile which it fecretes, is conveyed by 
tlie hepatic duCt iti-to the duodenum, within three or four 
inches of its origin; as (hewn in the Farriery Plate V. 
where this duct is feen to unite with the duodenum, above 
the colon. The pancreas is alio a glandular body, and le- 
■cretes a fluid (omewhat refeinbling faliva, which is co_n- 
Veyed by the pancreatic du£t into the duodenum, at the 
fame place where the hepatic du£t enters.—.Sec this gland 
delineated in the Farriery Plate VII. fig. i 2.—When the/e 
fluids (the bile and pancreatic juice) are poured into the 
inteftine, they mingle with the maf's of digefted food, 
which has been propelled by the ftomach, and feparate 
from it all thofe effential parts proper to be taken up by 
the lacleals, and which are fit to be converted into blood ; 
this procefs is termed chyhfaction. The lacleals open into 
the inteftines, and cover the whole of their internal fur- 
face, where they .are always difpofed to ablbrb tlte nutri¬ 
tious parts of the food in its pa (luge through the inteltinal 
canal. Hence fome phy(iologi/ls luppofe, that tf.e mouths 
of the ladteals have the power of /'electing fuch parts of 
the food as are fit to be converted into blood, that no 
previous feparation takes place, and that the bile ferves 
only as a natural purgative, conflantly ftimulating the in- 
tellines, thereby keeping up a fmall degree of motion in 
them, and promoting the expulfion of the feculent parts 
of the food. , 
The inteftines are principally conftrucled of mufcular 
fibres, fome of which run in a circular, and others in a 
Jongitudina/, direction : when the circular fibres contract, 
the diameter of the canal is diminiftied, and when the lon¬ 
gitudinal fibres are in action, it becomes Jhorter ; by the 
combined adtion of tlicfe fibres, the food is gradually pro¬ 
pelled through the whole of the inteftines. The motion 
thus excited may be diftindtly feen in an animal recently 
killed ; and in fome it continues a confiderable time after 
death. The inteftine, however, is not wholly compofed 
of mufcular fibres ; its internal furfuce is lined with a fine 
nervous and mufcular membrane, which is endued with 
«xqui(ite fenfibility, and has the power of forming on its 
Surface a mucous fubftance, which ferves to protect it 
from the adlion of acrimonious bodies. Befides the mul- 
oular and nervous coat, there is another which enters in¬ 
to the compofition of the inteftine, and this is a thin mem¬ 
brane called peritonaeum. The peritonaeum not only forms 
the third and external coat, but it likewife envelopes the 
whole of the abdominal vilcera, and is then fo reflected, 
as to form a kind of fac, in which they are all inclafed. 
Thus the inteftines are compofed of three coats, which 
are clofely in contact with each other; the peritoneal, the 
mufcular, and the nervous, coat. Over th.efe, and acrofs 
the veins and arte; ies, is to be traced the courfe of the 
‘lacleals, which are fpread upon the mefentery, whence 
they paf’s on towards the (pine, becoming larger and lefs 
numerous in their progrefs, till at length they terminate 
in the thoracic duel.—See the Farriery Plate VI,I. fig. 17, 
where their ramifications are diftinClly (hewn. 
The fpleen is a foft Ipongy vifeus of a bluifti colour, 
which is.found to differ in tize in different horfes. It is 
attached to the ftomach by veffels; it extends down the 
left tide to the kidney of that fide, to which it is at¬ 
tached. Its excretory duel has not yet been difeovered, 
and this renders its tile doubtful; it is however thought 
to uffift in digeftion. 
The kidneys are two glandular bodies, (ituated within 
the loins, or lumbar region, as delineated in the Farriery 
Plates IV. and VII. Their office is to feparate the urine 
from the blood. The urine, thus feparared, is conveyed 
by two tubes of confiderable length, termed ureters, into 
the bladder, which is compoled of three coats, like thofe 
of the inteftine ; and when it has received a Efficient quan¬ 
tity of urine to /limulate its mufcular fibres into aition, 
It contracts upon the urine, and forces it out through 
the urethra or urinary canal. 
No animal is more amply provided with the various 
Vol.VII. No.423. 
241 
apparatus belonging to the parts of generation, than the 
horfe ; for nature here feems to have lavithed whatever 
can tend to perieCl the generative organ. There is no 
property of the human cdnftriuStion of thefe parts, but 
what is found in tire horfe ; the moft material difference 
appears to conlift in the male, of the penis being fufpended 
from tire integuments of the abdomen, and not immedi¬ 
ately from the pubis, as in the human ; hence the acute- 
tvefs of the angle where it paffes the pubis, is fuch as to 
render the paffage of the catheter almoft impracticable. 
We have remarked, under the article Eqjcjus, that the 
penis of the horfe pofteffes a voluntary power of credlion, 
not known to the human, or perhaps to any other animal; 
this power is exerred on making water, and though the 
erection is not confiderable, it is yet fufficient to bring the 
penis from its (heath, which is effected apparently by its 
increafed gravity from blood accumulating in the cavern¬ 
ous cells of this part. After Haling, this femi-eredtion 
of the,penis fubfides, and it is again retracted within the 
(heath. The urethra of the horfe is mufcular from one 
extremity to the other, being formed on the outfide of 
ftrong tranfverfe flefhy fibres, and fupported by a ftrong 
ligament. 
Naturalifts were long at a lofs to difeover the mammae, 
or teats of the horfe ; they were at length detected by 
Buffpu, on the (heath of. the penis. M-r. John Hunter 
alfo difeovered this fact, without knowing that Buffion 
had previoufly noticed it; thefe male teats are larged in 
the foetus and young foal. In the glans penis, immediate¬ 
ly over the opening of the urethra externally, there is a 
large cell or cavity, fmooth on the infide, and lined with 
a membrane, which fecretes a brown unCtuous fubflance 
for the lubrication of the parts, and for defending them 
from the corrolive effects of the urine ; another cell of a 
fimilardefeription is oblervable on the fide of the urethra, 
and nearly furrounding it, and feparated from the former 
by a membranous partition. There is nothing refembling 
a fnentirn to the penis of the horfe, as in man; nor has 
the cavernous body of the penis any longitudinal feptum; 
its cells are divided by tranfverfe fibres, which are pro¬ 
bably mufcular ; it terminates in a point near the extre¬ 
mity otj the glans, where it is furrounded on every fide by 
the venous body, termed in the human corpusfpovgiqfimu 
Another Angularity in the genital parts of tins animal is, 
that there is an immenfe congeries of veins, lying on the 
back of the penis, which are filled during copulation, 
forming an elevation nearly as large as the penis itfelf; 
thefe veins communicate with both the cavernous and 
fpongious bodies; as delineated in the Farriery Plates IV, 
and VII. The vcj/culaeJaninales, and the bladders attached 
to them, are alio very large in the horfe, having integu¬ 
ments of confiderable thicknefs. 
The genitals of the mare differ from thofe of a horfe, 
not only as they are contained within the cavity of the 
belly, but likewife as to their figure and ufe. A mare 
has however two teftes, as well as the horfe, which lie 
backward on each fide under the loins; and tiiey are nou- 
iiHied with numerous arteries, which fpring from the 
aorta. Below thefe is feated the womb, or matrix, firmly 
tied in its place by two pair of ligaments. It is differently 
ftiaped from that of the human female, being divided by, 
its cornua, or horns, whofe hollow round inlertion feems 
to compofe its fundus, or bottom. The fubftance of the 
womb is flelhy, inclofed within two membranes, which 
are nervous and fentible. It has a great number of blood- 
veffels from the hypogaftrics, which, after conception, 
enlarge like a fponge, and fill the placenta with blood, not 
only that the womb may become a proper nidus for the 
feetus, but alfo to fupply it with fufficient iiourilliment. 
The vagina is an appendage to the womb, being a pro¬ 
duction ot its membranes; and is that part which forms 
the canal reaching from the pudenda, or externa! privi¬ 
ties, to the orifice of the womb. The udder is another 
pait peculiar to the mare, being that from whence the 
foal receives its firlt nourilhment after birth. Its lubftance 
3 QL. is 
