THE DIGESTIVE SYSTEM 97 



waste products, viz., hydrogen sulphide, ammonia, indol, and 

 skatol; and in various highly important nutrients, viz., several 

 different amino-acids concerning which more will be said later. 

 In some animals finely emulsified fat is split in the stomach but 

 most fat is digested in the intestines. 



At present our knowledge of the bovine stomach leads to the 

 conclusion that all or almost all of the fluid swallowed passes to 

 the rumen and not directly to the omasum, or third compartment, 

 as was at one time believed. This statement is based upon the 

 results of experiments in which the drinking water of cattle was 

 colored with magenta and the animals were slaughtered at the 

 end of several hours. 



In the paunch of cattle more than half of the cellulose is broken 

 down. This results in the production of large quantities of gas, 

 particularly CO2, H 2 , and CH4, which the animal belches at fre- 

 quent intervals. The factors concerned in this process will be 

 mentioned later. 



(C) Digestion in the Small Intestine. — During the process of 

 stomach digestion that portion of the ingesta which has been 

 acted upon by the gastric juice gradually feed into the small 

 intestine. 



Chyme is a watery solution of the products of gastric digestion 

 with a large quantity of undissolved, semi-digested matter in 

 suspension. It is soup-like in consistency, and contains most 

 of the fibrous parts of the diet, particularly cellulose. Shortly 

 after reaching the small intestine the acid chyme is neutralized 

 and then becomes alkaline from having been mixed with the 

 biliary, pancreatic, and intestinal secretions. These alkaline 

 digestive juices cause the acid albumin to precipitate which 

 changes the appearance of the chyme to a yellowish, frothy fluid 

 with clot-like particles held in suspension. 



Bile is secreted by the liver, from which it is conveyed to the 

 small intestine by the bile-duct. As the horse has no gall- 

 bladder, the flow of bile is continuous, but is much freer when 

 intestinal digestion is going on than in a fasting animal. In 

 other animals the bile is stored in the gall-bladder until required. 



A physical examination of bile shows that it is a watery fluid, 



alkaline in reaction, and very bitter to the taste. Fresh bile is 



yellowish-green in color, and has an average specific gravity of 



1005. According to Colin, from 250 to 310 c.c. of bile are secreted 



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