DIGESTION 217 



absorption, and he likens it to the stomach of ruminants and the 

 crop of birds. He further considers that the caecum exists owing 

 to the small size of the stomach, and the rapidity with which the 

 contents are sent along the small intestines. His experiments 

 demonstrated that the entire ' feed ' reaches the caecum between 

 twelve and twenty-four hours after entering the stomach, that it 

 remains there twenty-four hours, and during that time 10 to 

 30 per cent, of the cellulose disappears. 



The digestion of cellulose is no doubt a very important matter, 

 especially as we know that the poorer the food the more cellulose 

 digested ; but we are not prepared to admit that food necessarily 

 remains in the caecum twenty-four hours, and we believe that 

 cellulose digestion occurs principally, though not entirely, in the 

 colon, and, further, that it is not absolutely necessary for the 

 material to remain in the caecum, but that it may pass on at once 

 to the colon. The writer's experiments on digestion have shown 

 that ingesta may reach the caecum three to four hours after enter- 

 ing the mouth, and we are quite clear on the point that oats may 

 travel some considerable distance along the colon in four hours 

 from the time of being consumed, though this is regarded as 

 exceptionally rapid. For example, a horse which had never had 

 maize and had not tasted oats for two or three years, was fed 

 first with 2 J pounds of maize, and seventeen hours later with 

 4 pounds of oats. The animal was destroyed four hours from 

 the time of commencing to eat the oats. Much maize and a few 

 oats were found in the pelvic flexure of the colon, and a certain 

 proportion of maize and a quantity of oats in the stomach. In 

 twenty-one hours the small ration of 2.\ pounds of maize was 

 distributed between the stomach and pelvic flexure of the colon, 

 which is a very large area. In four hours the oats reached the 

 same point in the bowel that the maize had arrived at ; this is 

 exceptionally rapid, but this experiment supports two points it 

 is desired to emphasise — viz., the difficulty in getting the stomach 

 to empty itself completely, and the rapid transit of material 

 through the small intestines. 



Colin believed that in the caecum starch can be converted into 

 sugar, fats emulsified, and the active absorption of assimilable 

 matters occur. 



The Colon. — The direction taken by the colon of the horse is 

 remarkable. It commences high up under the spine on the right 

 side, its origin being very narrow, but it immediately becomes of 

 immense size ; it descends towards the sternum, and, curving to 

 the left side, rests on the ensiform cartilage and inferior abdominal 

 wall. The colon now ascends towards the pelvis, and here makes 

 a curve, the bowel becoming very narrow in calibre : the pelvic 

 flexure having been formed, the intestine retraces its steps 



