Digestive Organs of the Ox and Sheep. 
41 
of the milk. The internal tunic of the abomasum differs alto- 
gether from that of the other stomachs : it has a velvety appear- 
ance, and is therefore designated a villous membrane. The villi 
or shaggy projections of which it is composed are intimately 
connected with the secretion of the fluid referred to. The mem- 
brane lies principally in folds, most of which run parallel with 
the length of the organ ; at its entrance, two of them are so 
adapted as to prevent a regurgitation of the contents, and at the 
extremity, which communicates with the intestinal canal, they 
take an irregular course across the short diameter of the stomach. 
The abomasum is largest at its commencement, and gradually di- 
minishes towards its termination; it also turns upon itself, taking 
an upward direction (see e, fig. 2), and thus are formed its greater 
and lesser curvature. Tlie peculiar arrangement of the lining 
membrane, besides affording a large extent of surface for secre- 
tion, seems likewise to be well calculated to assist the passage 
of the chyme into the intestines mechanically ; as the cross rugae 
at the pylorus tend to support the weight of the mass passmg 
through it, while the longitudinal plaits present no obstacle to its 
progress. 
Digestion is mainly, if not entirely, a chemical process, in which 
the hydrochloric and acetic acid of the gastric juice play the chief 
part. To enter fully into this subject would divert us from our 
project, and therefore we proceed to speak of the changes effected 
in the intestinal tube on the chymous matter. We will first, how- 
ever, make a few observations on the development of the stomachs 
of the calf during the period of lactation. These viscera present 
a striking contrast with the fully formed stomach of the adult 
ruminant, for we find the abomasum to be the largest, and to 
be the only one actively employed at that time. This arises from 
the fact that the milk requires no preparation to suit it for diges- 
Fig. 7. 
(I, The Rumen 6, The Omasum. c, The Abomasum. 
