Digestion. 14.5 



would never have occurred to me that the fluid material 

 of the small intestines passed to and fro between the 

 stomach and the ileum, exposed twenty times over, as 

 Colin expresses it, to the absorbent surface of the bowels. 

 He must have observed this as the result of his vivisections. 

 Experiment shows that water will pass from the stomach 

 to the ca?cum in from five to fifteen minutes. By applying 

 the ear over the duodenum as it passes under the last rib on 

 the right side, I have heard the water which a horse at that 

 moment was drinking rushing through the intestines on its 

 way to the ca?cum. 



One is always struck by the fact that the small intestines 

 are never seen full, in fact, are often practically empty. 

 From this I judge that material passes very rapidly through 

 them. This material is always in a liquid condition 

 excepting at the ileum ; the fluid is derived from the 

 secretions poured into and originating in the bowel, and 

 that active absorption goes on in the intestines is proved by 

 the difference in the physical characters of the contents, say 

 in the middle of the small intestines and at their termination. 

 The rate at which the chyme passes through the small 

 intestines will vary with the nature of the food, and the 

 frequency with which the horse is fed. Ellenberger says 

 it reaches the csecum six hours after feeding, but has not 

 entirely passed into this bowel for twelve or even twenty 

 hours. I have known it reach the crecum in four hours. 



The remaining digestive fluids which the chyme meets 

 with in the small intestines are the bile and pancreatic 

 juice ; the action of these on food is described in the 

 chapter dealing with the liver and pancreas. The little we 

 know about the absorption of lymph and chyle, and their 

 elaboration before reaching the blood, are points which 

 must be reserved for the chapter on ' Absorption.' 



Large Intestines. — There can be no doubt that in solipeds 

 digestion in the large intestines is a very important process; 

 at least, we judge so from the fact of their enormous 

 development. In many respects they present a consider- 

 able contrast to the small intestines ; for instance, they are 



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