936 
arteries, its veins, its nerves, and its lymphatics 
passing to and from it, and the whole must be 
invested by a single shut sac without loss of 
continuity. The complexity thus arising de- 
mands for this membrane a lengthened descrip- 
tion. 
We propose, first, to trace its continuity 
throughout its entire extent; next, to describe 
the sheets with two free surfaces, which it 
forms by duplication; thirdly, to examine the 
manner in which it invests each of the viscera, 
and the abdominal parietes, that is to say, the 
extent to which it does so in the case of each, 
the point at which it arrives at and quits each, 
and so on; and, lastly, to describe its con- 
' nexions, or the adhesion of its external surface, 
varying in intimacy, with the parts which it 
invests. The most important points connected 
with the anatomy of the peritoneum will be 
incidentally involved in the consideration of 
the first of these propositions. 
ConTINUITY OF THE PERITONEUM.—To 
demonstrate the unbroken continuity of the 
peritoneum, we are compelled, in description, 
to trace it in various directions, starting 
from a certain point and following it up till, 
having performed a complete circuit, we 
return again to our starting point. In doing 
so we shall avoid restricting ourselves to the 
mesial or any other sectional line. We believe 
that such a restriction, closely adhered to, 
tends to convey an erroneous impression, 
namely, that of a line instead of a superficial 
expanse. In thus tracing the peritoneum, it 
is better to let the mind rest upon the idea of a 
free surface, rather than upon that of a mem- 
brane. By a membrane one is apt to under- 
stand a separable skin; but in some situations 
not only is it impossible, by any ordinary ma- 
nipulation, to separate the peritoneum from its 
connections, but two layers of it often form 
together a structure so thin that one can hardly 
help regarding it as a single membrane. In 
no instance is any part of a serous membrane 
free on both its surfaces. The external surface 
of the peritoneum, like that of all other serous 
sacs, is every where adherent, either to the sub- 
jacent structures, or, as in its duplications, to 
itself; whilst, on the other hand, its internal 
surface is, normally, every where free. It 
follows then, that wherever, in the peritoneal 
cavity, the finger can be placed on a free sur- 
face, there is a layer of peritoneum immedi- 
ately beneath it; that if a continuous free 
surface is demonstrated, the continuity of the 
serous membrane is proved; that in fact a free 
serous surface represents a layer of serous 
membrane, and may be described instead of it 
when continuity alone is sought to be proved. 
We shall therefore at present use the expres- 
sions free surface and layer of serous mem- 
brane as synonymous ; the free surface of a 
viscus instead of the serous membrane invest- 
ing a viscus. 
When the abdominal cavity is laid open in 
front by a crucial incision, the inner surface of 
the reflected flaps is seen to be free, glistening, 
and of a pale red colour. By a slight exami- 
PERITONEUM. 
nation of the cut edges this is found to be the 
free surface of a membrane, whereof the other 
surface is connected to the subjacent structures 
by areolar tissue: the free surface is the parietal 
serous surface of the abdomen: the membrane 
is the parietal portion of the peritoneum. If 
an incision has been carried from the navel to 
the xiphoid cartilage, a falciform, membrane- 
like process, strikingly resembling the freenum 
lingue, is seen connected with the anterior 
parietal peritoneum, a little to the right of the 
middle line, projecting backwards, and towards 
that aspect presenting a free concave border. 
It is the falciform ligament of the liver. The 
base or broadest extremity of the falx is sessile 
along an antero-posterior line upon the uppe 
surface and anterior edge of the liver; which 
line corresponds with and runs into the 
antero-posterior fissure on the under surface of 
the liver; and this fissure receives the round 
ligament, and consequently the free edge of 
the falx which encloses it. The apex of the 
falx is at a point on the inner surface of the 
anterior abdominal parietes, co ing to 
the navel. The surfaces of the falciform liga- 
ment are continuous with the serous surfaces of 
the parietes and liver; its free border, as inci- 
dentally mentioned above, encloses a structure 
called the round ligament of the liver, which 
gives a considerable thickness to this 
The round ligament of the liver is the umbi- 
lical vein of the foetus, degenerated to a fibrous 
cord in the adult, and it runs across, as that 
vein did, from the navel to the antero- or 
fissure of the liver, defining the free border of the 
falciform process in question. The composition, — 
then, of the falciform ligament of the liver is— 
a portion of peritoneum doubled or folded, so 
that its outer surface is brought in contact with 
itself, as happens when asheet of paper is folded 
so as to make two leaves. The two surfaces 
thus brought into contact, are united together 
by areolar tissue, as if the two leaves were 
stuck together with paste ; and the round liga 
ment lies along in the extreme edge of the fold, 
like a string that holds a sheet of two leaves in 
a book-cover. The vessels necessary for the 
nutrition of these structures ramify in the ic 
terposed areolar tissue. It seems as if 
umbilical vein, in making the shortest | out 
from the navel to the longitudinal hepatic fi 
sure, had carried back before it a fold of 
superjacent peritoneum. f aed 
e have spent more time in describing th 
the first peritoneal fold we have come to, t 
is due to its importance, because it affords | 
that which we want in this early stage of | 
description, an instance of the manner in whi 
the peritoneum invests the various orga 
having the advantage of extreme simplit 
A bowel is invested by the peritoneum and 
occupies a situation in a fold precisely am 
gous to that which the round ligament oceup 
in the falciform ligament; whilst the vess 
and nerves of the bowel to and f 
imbedded in the areolar tissue uniting the 
posed surfaces. ae. 
Placing a finger of each hand on each sid 
