*44 
ANA T O M Y, [Gravis Uterus, 
.abforbed juices. At this time, the ovum abounds with a 
great proportion of a limpid watery liquor, which, like 
•the white of an egg, hardens by heat, or by mixture with 
alcohol. The foetus remains long invisible, being never 
feen before the feventsenth day, when it is an unformed 
mafs of mere mucus in a cylindrical lhape. When fome 
distinction of parts is viliblc, it has a very great head, a 
frnall /lender body, no limbs, and is fixed by a broad flat 
navel to the obtufe end of the ovum. Henceforward the 
foetus continually increafes as well as the ovum, but in an 
unequal proportion: for while the arterial ferum is con¬ 
veyed by more open paffiages into the veffels of the ovum, 
the foetus, which feeins to receive, by its very capacious 
umbilical vein, the greatest part of the nouriflunent, in¬ 
creafes very fait. The ovum alfo increafes, but in a lefs 
degree; and the proportion both of it and its water to the 
foetus continually diminiihes. The fleecy productions of 
the ovum lefi'en, they do not cover fo much of its furface, 
and are gradually covered with a continued membrane., 
Thofe, however, which fprout from the obtufe end of the 
•ovum increase, and are by degrees formed into th <z placenta. 
Such is the general appearance of the ovum in the fe- 
cond month; from which time it changes only by increa¬ 
sing in bulk. That part of the ovum fixed to the uterus 
makes about a third of its whole furface, and is in the 
form of a flat round dilh or plate; fucculent, fibrous, full 
of protuberances, but throughout perfectly vafcular; 
thele tubercles change into others of the fame kind; it is 
for the molt part accurately, and often infeparably, con- 
TicCted with the uppermoft part of the uterus. This fub- 
flance, called the placenta, is remarkable for its large vef- 
fels, is of a thin cellular texture, and collects the velFejs 
.every where, but chiefly in the circumference of its great- 
>elt circle ; the exhaling arteries of the uterus correfpond- 
ing with the veins of the placenta, and the arteries of the 
placenta with the veins oi the uterus. In the common 
furface of the uterus and placenta, a communication is 
made, by which the uterus fends to the foetus, firlt that 
white ferous liquor not unlike milk, and laltly, as it feems, 
red blood itfelf. This communication of the humours 
feems to be demonfitrated by the fupprefllon of the menfes 
in women with child, whofe blood mull be turned into 
another channel; by the iofs of blood which follows a re¬ 
paration of the placenta in a mifcafriage; and by the blood 
of the foetus being exhaufted from an haemorrhage in the 
mother; by haemorrhages that enfue from the navel-firing, 
fo as to kilt the mother when the placenta has been left 
adhering to the uterus; and, laltly, by the palfage of wa¬ 
ter, quickfilver, tallow, cr wax, injected from the uterine 
arteries of the mother intp' the veifels of the placenta, as 
is confirmed by the mofbfeithful obfervations of eminent 
.unatomifrs, That blood®sYent into the foetus is evinced 
by the magnitude of the armies of the uterus and placen¬ 
ta; the diameter of the terpentine arteries of the uterus; 
the hemorrhage that follows, even when the placenta is 
very fiightly "hurt; but especially by the motion of the 
blood, which, in a foetus definite of a heart, eouid only be 
given to thetvu.mours.of the foetus by the blood of the mother. 
The nourithment of the fetus, from the beginning to 
the end of its full time, is without doubt conveyed to it 
through the umbilical vein. This vein, arifing from the 
•exhaling veffels of the uterus, and from the umbilical ar¬ 
tery with which it is continuous, makes the venous firm, 
fies under the furface of the placenta; when all its branch, 
-es are collected, it forms a large trunk that is twilled, 
though not fo much as its concomitant arteries, into cir- 
cular folds 5 it is fuffieien.tly long to allow a free motion : 
after being ftirroutided with cellular mucus including alfo 
other velfiels, and the whole being covered with a conti¬ 
nuation of the amnios, it is known by the name of the 
umbilical cord, The umbilical vein, after forming fome 
protuberances, enters through the navel, in an arch made 
by a parting of the (kin and abdominal mufclcs, and goes 
to the proper finus of tin- liver, into which the fmaller 
portion of the blood that it conveys is poured through the 
fiender ductus ver.ofus Into the vena eava feared in the 
poftcrior- "fofla of the liver; f.t the greater part, of its 
ifiood T’oes through the large hepatic branches, which 
confiantlv arife from its fulcus, and remain even in the 
adult; and the blood goes thence to the heart by the con¬ 
tinuous branches • of the ver.a cava. The finus, or left 
branch of the vena portarum itfelf, is a part of the uml 
bilical vein, and its branches bring the blood from the 
placenta to the cava, while the right branch alone carries 
the mefenteric and fplenic blood through the liver. 
But this is not all the ufe of the placenta; for the foe¬ 
tus fends great part of its blood to the placenta by two 
large umbilical arteries, which are continued in the direc¬ 
tion of the aorta; and, after giving fome Header twigs to 
•the femorals, with Hill fmaller arteries to thepelvis, they 
afeend reflected in the direction of the bladder, furround- 
ed with the cellular plate of the peritonaeum, and with 
iome fibres fpreading to them from tire bladder and ura¬ 
chus ; they then proceed on the outiide of the peritoneum 
into the cord at the navel, in which, palling alternately in 
a (trait and contorted courfe, they form various twiftings 
and windings, fomewhat (harper than thofe of the vein 
which they play round; and at laft they arrive at the pla¬ 
centa, whofe fubfiance is entirely made up of their branch¬ 
es, in conjunction with thofe of their correfpooding veins, 
and a fiippery cellular fubfiance following both velfiels; fo 
that the kernels themfelves, that are confpicuous in the 
placenta, are convolutions of thofe velfiels. By thefie 
branches the biood"feems to pals through the minuter 
arteries of the placenta into the veins of the maternal ute¬ 
rus, that after undergoing the abtion of the lungs by the 
mother’s refpiration, it may return again in an improved 
Hate to the foetus. What other reafon can be uffigned for 
fuch large arteries, which carry off above a third part o.i 
the blood of the feetus? 
But it will perhaps be afked, Whether the feetus is noil- 
riffled by the mouth likewife ? Whether it drinks the lym¬ 
phatic liquor contained in the cavity of the amnios, which 
is coagulable unlefs putrefied, and in the middle of which 
the feetus fwims, and whofe origin is not fufficiently 
known ? Whether this opinion is not in fome meafitre con¬ 
firmed by the open mouth of the feetus, and the analogy 
of chickens, which are under a neceffity of being nou- 
ri fired from the contents of the egg only? to wdiich add 
the abfence of anavel-ftring in fome fostufes; the quanti¬ 
ty of meconium filling the large and part of the frnall in- 
teftines; the fimilitude of the liquor found in the cavity 
of the ftomach to that which fills the amnios; the propor¬ 
tionable decreafe of the liquor amnii, as the foetus en¬ 
larges ; the glutinous threads which are found continued 
from the amnios through the mouth and guilt, into the 
ftomach of the foetus; the true faeces found in the ffomach 
of the foetus of quadrupeds; the open mouth of the foe¬ 
tus, which we have accurately obferved ; the gaping of a 
chicken fwimming in this liquor, and its attempts as it 
were to drink it up? Again, What are the fountains or 
fpring's from whence this lymph of the amnios flows ? 
whether it tranfudes through tire invisible veffels of the 
amnios, or .through certain pores from the fucculent cho¬ 
rion, which is itfelf fupplied from the uterus ? It muff 
be confefled, that tflefe inquiries labour under obfeurities 
on all Jidesj notwith(landing which, fays Haller, there 
feems more probability for them than otherwife, -fince the 
liquor is of a nutritious kind, at lead in the fir fit begin¬ 
nings of the feetus, and is derived from the uterus. 
The foetus continues to advance in growth; the limbs 
gradually fprout from the trunk, under the form of tuber¬ 
cles ; and the other outworks of the human fabric are by 
degrees beautifully finffhed, and added to the reft. The 
manner in which ail this is performed anatomifts have not 
hitherto fufficientiy deferibed, We final! not therefore 
enter fully on the fubjeel; yet it feems neceflary to fu’o- 
wit the following compendium to the reader’^ c^nfideration. 
The embryo which we ftrft obferved in the uterus of the 
mother was k gelatinous matter, having-fcarcely any pro- 
