FUNCTIONS PEEFOEMED BY THE BLOOD. 65 



position. The bile acts as a natural purge, the bowels 

 becoming constipated when it is deficient in quantity. 

 It also, by reason of its antiseptic properties, prevents 

 decomposition of the ingesta, prior to their being ex- 

 pelled. In the absence of bile, deleterious gases are 

 evolved in the intestines, and are absorbed into the 

 system, to the detriment of the health of the animal ; 

 in which case the dung has a foul smell. Bile is con- 

 stantly being excreted by the liver. We find that 

 certain of the higher animals, such as man, are pro- 

 vided with a gall-bladder, into which this fluid collects, 

 to be poured out into the intestines during the process 

 of digestion, which is, in these cases, intended by 

 nature to take place at certain intervals. The horse, 

 however, possesses no gall-bladder, which fact clearly 

 indicates that he should be, more or less, constantly 

 supplied with food. The fact of his stomach being of 

 small capacity, and his intestines of large size, points 

 to the same conclusion. 



On leaving the small intestine, which is about 72 

 feet long, the food becomes collected into a capacious 

 cul-de-sac the caecum formed by the large intestine, 

 the length of which is about 20 feet. The caecum 

 appears to be a kind of supplementary stomach, 

 in which is collected the pulpy mass of water and 

 unassimilated food, which the stomach and small 

 intestines have failed to take up. Here the remaining 

 nutritive particles are dissolved out and absorbed. The 

 caecum can contain about 6 gallons of fluid. 



Functions performed by the Blood. As the 

 nutritive part of the food becomes changed into forms 

 capable of being assimilated, it becomes gradually 



F 



