178 
the gall- bladder contains bile, and the mucous 
membrane becomes rugous and reticulated. 
At the eighth month, and during the ninth and 
tenth months, the liver becomes still more ho- 
rizontal in position and of a deep red colour. 
The bile is more abundant and of a clear green 
tint. Atthe tenth month, that is, at birth, the 
relative proportion of the liver to the rest of 
the body is as 1 1018 or 20; the average in 
the adult being as 1 to 36. After birth the 
size and weight of the liver diminish until the 
end of the first year, for, according to Meckel, 
the liver of the newly born infant weighs one- 
fourth heavier than at the age of eight or ten 
months. The borders of the liver are rounded 
in the foetus, and the inferior surface is convex. 
The lobes are nearly equal until birth, after 
which the left diminishes in size, the right re- 
maining stationary or growing but little, and 
at the age of one year the left lobe is scarcely 
one-half so large as at birth. The texture of 
the liver in the fetus is soft and fragile and 
apparently homogeneous in structure; during 
the earlier periods its colour is a light brownish 
grey; at about the mid-period it becomes 
deeply red, and after birth loses a portion of 
its colour from a diminution of the quantity of 
blood circulating through it. 
Uses of the liver—The liver performs two 
most important functions in the animal eco- 
nomy :—1, it separates from the venous blood 
of the chylopoietic viscera certain elements 
which are needful to digestion ; and, 2, it de- 
purates the venous blood. The first of these 
fur.ctions constitutes the secretion of bile. 
The second is evinced in a comparative exami- 
nation of two of the great depurating organs, 
the lungs and the liver, in the various classes 
of animals, where the latter will be constantly 
found in exact relation with the development 
of the respiratory organ, and with the neces- 
sity for the removal of a larger quantity of 
hydrogen and carbon from the blood. Thus, 
in herbivorous animals, the liver is small ; it is 
small also in monkeys and in man. It is large, 
and has reached its highest development 
amongst Mammiferous animals in Carnivora. 
In birds it is larger in proportion than in Car- 
nivora, from the greater necessity of a highly 
oxygenated blood in that class of animals. 
In Reptiles, with cold blood and a low degree 
of respiration, it is large; it is large also and 
for the same reason in Fishes; and very large 
among the Invertebrata. 
Secretion of bile—The bile, which would 
appear, from the existence of follicular recesses 
in the alimentary canal, to be produced in all 
animals from the lowest to the highest, is 
secreted in man and in vertebrata from the 
blood during its circulation through the lobu- 
lar venous plexus in the lobules of the liver. 
Hence it becomes a question of importance to 
physiology to decide from what kind of blood 
it is elimmated. If, according to Kiernan, all 
the arterial blood of the hepatic artery become 
venous previously to its passage into the lo- 
bular venous plexus, the 
from venous blood ; that venous blood being 
NORMAL ANATOMY OF THE LIVER. 
ile must be secreted ~ 
derived from the capillaries of the ch 
organs, and from the capillaries of the 
artery. I have given Kiernan’s reasons 
belief that this is the truth; and in corrobo- 
rating the results of his injections I mustalso 
add my own testimony to his view of the ; 
cretion of the biliary fluid. Miiller, ente 
taining, as I have already shewn, a differei 
opinion with regard to the distribution of th 
vessels of the liver, believes that the bile 
secreted from a mixed arterial and ven 
blood, resulting from the termination of be 
the hepatic artery and portal vein in the “y 
cula ultima reticulata,” or lobular ven 
a From the undecided manner in wi 
e expresses this opinion, I am temp 
give the quotation in which it is con 
that my readers may judge how far he be re 
in earnest in his assertion. “ It is known tha 
injection thrown either into the hepatic art 
or into the portal vien, fills the same capil 
net-work, from which, on the other hand, 
hepatic veins likewise arise.” : 
Since reading the above paragraph I hi 
injected twelve livers for the purpose of : 
ciding the question, in my own mind, of 
ultimate termination of the hepatic 
I have in no instance succeeded in foremg 
jection into the lobular venous pas t 10 
every other of the organ has been beau 
fully injected. I have therefore been forces 
the conclusion that some ee must € 
with regard to this passage, and that, altho 
—— true ihibaectitinda to the portal ve 
iiller cannot mean that the capillary” 
work (lobular venous plexus) from which t 
hepatic veins arise, is actually filled fron t 
hepatic artery. But he continues, “ It 
ars, therefore, that the arterial blood of the 
epatic artery, and the venous blood of 
porta, become mixed in the minute vessé 
of the liver, and that the secretion of 
probably takes place from both.” Now, w 
deference to Miller’s judgment, the ky ic 
with our present knowledge upon t 
anatomy of the liver, ought not to be one 
serena or surmise ;—does it? or does it nt 
ut he appears far from satisfied, in relyi 
for the support of his argument upon his oF 
peculiar theory of the arrangement of the | 
patic vessels, and, as if distrusting its é 
ency, he exclaims in another page of his P 
siology, “ But the possibility of bile b 
secreted from arterial blood is demonstrat 
by the cases in which the vena porte enters 
vena cava directly instead of being distribut 
through the liver. Mr. Abernethy observed 
anomalous structure in a male child ten mon 
old; and Mr. Lawrence has detailed a case 
which the same malformation existed in a chil 
several years of age. In Mr. Abernethy’s ea 
however the umbilical vein was still 
and branched out in the substance of 
it is possible therefore, as Mr. Kiernan remarks, - 
that the arterial blood, after having nourished — 
the liver, was poured into the branches of the — 
umbilical vein, just as it is in the normal con= 
dition, according to his opinion, poured into— 
& 
"sy 
