60 GENERAL ANATOMICAL CHARACTER 
“agminated” glands ; the latter being more commonly known by the 
name of “Peyer’s patches.” These were formerly supposed to be 
secretory organs, which discharged some kind of fluid into the 
intestine, but are now more generally considered to belong to that 
group of structures of somewhat mysterious function of which the 
lymphatic and lacteal glands are members. The solitary glands are 
found scattered irregularly throughout the whole intestinal tract ; 
the agminated, on the other hand, are always confined to the small 
intestine, and are most abundant in its lower part. They are 
subject to great variation in number and in size, and even 
in different individuals of the same species, and also differ in 
character at different periods of life, becoming atrophied in old 
age. 
i Liver.—The distinct glands situated outside the walls of the 
intestinal canal, but which pour their secretion into it, are the 
pancreas and the liver. The latter is the more important on 
account of its size, if not on account of the direct action of its 
secretion in the digestive process. This large gland, so complex in 
structure and function, is well developed in all mammals, and its 
secreting tube, the bile-duct, always opens into the duodenum, or 
that portion of the canal which immediately succeeds the stomach. 
It is situated on the right side of the abdomen in contact with the 
diaphragm and the stomach, but varies greatly in relative size, and 
also in form, in different groups of mammals. In most mammals a 
gall-bladder, consisting of a pyriform diverticulum from the bile- 
duct, is present, but in many this appendage is wanting, and it is 
difficult to find the rationale of its presence or absence in relation 
to use or any other circumstance in the animal economy. 
The descriptions of the livers of various animals to be met 
with in treatises or memoirs on comparative anatomy are very 
difficult to understand for want of a uniform system of nomencla- 
ture. The difficulty usually met with arises from the circumstance 
that this organ is divided sometimes, as in Man, Ruminants, and 
the Cetacea, into two main lobes, which have been always called 
respectively right and left, and in other cases, as in the lower 
Monkeys, Carnivora, Insectivora, and several other orders, into a 
larger number of lobes. Among the latter the primary division usu- 
ally appears at first sight tripartite, the whole organ consisting of a 
middle, called “ cystic” or “suspensory ” lobe, and two lateral lobes, 
called respectively right and left lobes. This introduces confusion 
in describing livers by the same terms throughout the whole series 
of mammals, since the right and left lobes of the Monkey or Dog, 
for instance, do not correspond with parts designated by the same 
names in Man and the Sheep. There are, moreover, conditions 
where neither the bipartite nor the tripartite system of nomencla- 
ture will answer, so that we should have considerable difficulty in 
