SHEEP diseases: causes, nature and prevention. 213 
mesenteric glands, the kidneys, the spleen, the lungs and the skin. 
Digestion .—The first act of digestion is performed in the 
mouth, when food is broken up by the teeth and exposed to the 
action of the saliva , which secretion converts the starcy matter it 
contains into sugar by the action of a ferment (ptyalin). The 
process is most perfect in ruminants. The second act in diges¬ 
tion takes place in the stomach, where the acid secretion—gastric 
juice (succus gastricus)—dissolves mineral and other matters, 
while by the action of a second ferment (pepsin) albumen is ren¬ 
dered more soluble and converted into substances known as pep¬ 
tones. The third act in digestion is performed in the small 
bowels, where the food meets with the secretion of the pancreas 
(sweetbread), the pancreatic juice; and with the secretion of the 
liver, the bile. The bile also contains a ferment which, to some 
extent, also converts starch into sugar. It is alkaline, and in a 
slight degree dissolves and emulsifies fats; it is also supposed to 
act as a natural purge in the intestines, and to prevent decompo¬ 
sition by acting as an antiseptic. 
The pancreatic juice (succus pancreaticus), like the bile, is alka¬ 
line ; it converts starch into sugar to a much greater extent than 
does the saliva, and as in the gastric juice, so in this, a ferment 
(trypsin) exists, which has the power of converting albumen into 
peptones; it also splits up and emulsifies fats: both bile and pan¬ 
creatic juice convert a small quantity of fat into soap. 
Into the small bowels a Secretion is poured, known as the in¬ 
testinal juice (succus entericus) which, in a modified degree, assists 
the other juices mentioned. 
In the large bowels, acidity replaces alkalinity and certain con¬ 
stituents of the food are rendered soluble and probably digested. 
Some of the soluble matters of the food are absorbed partly 
from the stomach, but more largely from the intestines; the more 
important constituents are mainly taken up from the small intes¬ 
tines by the lacteals and the tributaries of the portal vein. 
It is evident, from what has just been stated, that perfect and 
healthy digestion and the nourishment of the blood and the tis¬ 
sues depends entirely upon the perfect and healthy action of the 
important organs to which I have referred. 
