The BO'O.K. of 
veffels. Beneath the tefticles, and under the 
skin of the kidneys, there lie two other fingular, 
and ftrange bodies, xm, but I neglected duly 
examining them. 
The vas deferens grows finaller by degrees, fo 
as to form but one trunk, oo, but foon again it 
dilates confiderably, and in this part we may 
diftinétly fee the feminal veficles lying againft it, 
pp. Thefe veficles do not differ in conftruction 
from the correfpondent veffels in man, and other 
animals, except in regard to their being of a 
more membranaceous fubftance. They open 
into the vafa deferentia, and convey to them from 
a great many little cells, an aqueous feminal 
fluid, which is perhaps the vehicle of the true 
{perm. In fine, both thefe veficles, and the vafa 
deferentia are inferted into the furface of the rec- 
tum, 79, directly under the bottom of the urina- 
ry bladder, where I have reprefented both their 
mouths, by two openings that appear through 
the ftraight gut. Upon this laft inteftine lies a 
double urinary bladder, ss, into which the urine 
is conveyed by thofe ureters, which at the fame 
time perform the office of the vafa deferentia. 
When firft I difcovered thefe vafa deferentia, I 
immediately fearched for the ureters, with a 
great deal of attention, as I could hardly think, 
that a veffel of fuch importance could ferve two 
fuch different purpofes. But I afterwards found, 
that the ureters of the female Frog, were con- 
ftructed in the fame manner as thefe veficles in 
the male ; and by this difcovery, I became tho- 
roughly acquainted with all thefe parts. I have 
accordingly exhibit them, as they appeared in the 
fmaller Frogs, as may be feen by infpecting the 
fecond figure. 
It is now time to fay fomething of the genital 
parts of the female: thefe are an ovary, uterine’ 
tubes, or horns of the uterus, and the uterus itfelf. 
The ovary lies upon the uterus, with which it is 
always united; and near the fame place are the 
fatty appendages, which I defcribed in the male 
Frog, when | treated of the genital parts. ‘The 
ovary, which is always double, equally occupies 
the right and left region, and is conftantly found 
fabdivided into lobules. I have feen them, to the 
number of five, on a fide in fome Frogs. Na- 
ture, however, does not always obferve the fame 
order in this particular, except that the ovary 
never appears, but divided into more or lefs of 
thefe parts, The blood veffels are principally 
diftributed through thefe divifions of the ovary, 
‘Tab, XLVII. Fig. rt. 2, and afterwards they 
diffafe themfelves all over it, Each lobule is 
hollow, and wrapped up in its own particular 
coat; fo that, by fixing in alittle tube, f, it may 
be eafily diftended with air, and feparated from 
the neighbouring lobules, 4. ‘This muft be done 
very cautioufly, becaufe this coat is fo tender, 
that anything of a rough blaft would burft it. We 
may then plainly perceive, that all thefe lobules 
are confined, each to its own limits, and have 
not the leaft communication one with another, 
‘As the coats invefting the lobules of the ovary 
"are fo very delicate, the eggs may be feen thro’ 
them diftinétly, ¢c: a perfon that was not very 
cautious, by directing his eyes and hands to this 
106 
( 
NA RE Ee Ot, 
part, might eafily fancy to himfelf, that the eogs 
lay on the outfide of the ovary. Thefe eggs use 
black, and perfectly round, and generally they 
have a white or yellow fpot in the centre. They 
lie clofe to the internal furface of the coa‘s or 
membranes that conftitute the lobules of the 
ovary, and are fixed there by the blood veffels, 
asit were, by fo many fhort little flalks. ‘This 
circumftance is very vifible, in cutting off one or 
two of the lobules of the ovary, d, for then the 
enclofed eggs fhew themfelves moft diftin@ly. 
But this experiment cannot be conveniently 
made, unlefs about the beginning of March, or 
a little afterwards, as it is chiefly at that feafon, 
that the ovaries abound with perfect eggs: this 
is moreover the propereft time for examining the 
genital organs. On examining carefully the ovary 
at this period, we may likewife find in it a {pe- 
cies of eggs different from thofe I have now de- 
fcribed, Thefe are fmaller, white at firft, and 
when pretty. well grown, yellowith. Thefe laft 
eggs, however, are only the rudiments, not 
yet perfected; and therefore, they remain in the 
ovary, after it has difburthened itfelf of all the 
perfect eggs. But before I treat of this opera- 
tion, I think proper to defcribe the uterine tubes 
or horns. 
In Frogs, thefe tubes arife very high in the 
breaft, from whence they ftretch in the middle, 
from one end of theabdomen to the other, and ter- 
minate in theuterus, with which they lie concealed 
in the lower part .of the belly, but fo as to be 
able to move higher, according as the uterus di- 
lates or contracts itfelf, Every Frog has two 
fuch tubes, which are placed, one at one fide 
of its body, and the other at the other fide, 
Properly {peaking, the fuperior part of the 
tube lies near the heart, and is connected on each 
fide by the ligament, by which the liver alfo is 
fufpended. In the fame place, where part of 
the peritoneum pafling freely over the: heart and 
pericardium, forms with the liver a diftiné&t ca- 
vity, in which the heart, wrapped up in its peri- 
cardium, lies under the breaft bone, as in the hol- 
low of the mediaftinum or diaphragm. To fee all 
thefe particulars diftinGlly, itis neceflary to lay open 
the Frog’s belly a little higher than the extremity 
of the breaft-bone, where this bone degenerates 
intoa cartilage; then cut off the membranaceous 
parts; and laftly, turn over the breaft-bone upon 
the head, and fecure it in that pofture with a pin, 
Tab. XLVII. Fig.1v.a, Thus we difcover a con- 
fiderable cavity above and about the point of the 
heart, 5, in which the heart lies hid with its peri- 
cardium, under the breaft-bone, as within the dia- 
phragm. At the fame time, we may {ee on each 
fide of the heart, the extreme ends or natural 
openings of the tubes, ¢ ¢, which moft firmly and 
immoveably grow there to the peritoneum, and td 
the ligament, by which the liver is fufpended, 
fo that they cannot reach to the ovary, which 
lies at too greata diftance from them, Befides, 
thefe tubes are very flender and delicate.. They 
bend a little, efpecially where they lie upon the 
lungs; for they ftretch over the lungs and the 
liver, where they arife from very flender mem- 
branaceous beginnings. For this reafon, they 
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