INTESTINAL DIGESTION. 193 



Intestinal Digestion; Chylification. 



212. The process of digestion is by no means completed in. 

 the stomach j for much of the matter which escapes from it 

 in the chyme, is destined to undergo a further change whilst 

 passing through the intestinal canal ; especially in the her- 

 bivorous tribes, whose food, being less digestible than that of 

 the carnivorous races, requires to be longer delayed in the 

 intestinal canal, in order that it may yield up its nutritious 

 portion. Hence we find this canal of enormous extent in 

 most animals whose food is vegetable, being in the Sheep 

 about twenty-eight times the length of the body ; in the 

 purely carnivorous animals, on the other hand, it is compara- 

 tively short, being in the Lion only about three times the 

 length of the body, while in the Serpent it runs almost 

 straight from one extremity to the other ; and in animals 

 which live on a mixed diet, it is of medium length, being 

 in Man about six times as long as his body. The intes- 

 tinal tube is usually distinguished into the small and the 

 large intestine ; of which the small is the first portion, and 

 the large the second. The former, as shown in fig. 108, is 

 disposed in a convoluted or twisted manner, so that a great 

 extent of it may be packed within a small compass ; it 

 usually forms about three-fourths of the whole length of the 

 canal It is held in its place by a serous membrane termed 

 the peritoneum, which forms an immense number of folds 

 that suspend it (as it were) from the vertebral column ; but 

 these still allow it a considerable power of movement. 



213. Soon after passing from the stomach into .the intes- 

 tinal canal, the food is mingled with three secretions, which 

 have an important influence on the changes it is further to 

 undergo ; these are the Bile, the Pancreatic fluid, and the In- 

 testinal juice. The two former are prepared by two large glan- 

 dular masses, the Liver and the Pancreas (or sweetbread), 

 which, in all the higher animals, are completely detached 

 from the alimentary canal, and send their secretions into it 

 through special ducts ; the latter, like the gastric juice, is 

 formed in little follicles lodged in the wall of the canal itsel 

 The peculiar matter which forms the chief solid constituent of 

 bile, is essentially a soap formed by the union of two resinoid 

 acids, with soda as a base ( 364). The composition of ttie 



