CHAPTER XI 

 THE LARGE INTESTINE 



THE material passing into the colon is dilute and much 

 reduced in volume as compared with the chyme passing out 

 of the stomach. In the lower part of the small intestine 

 the absorption of water more than counterbalances the 

 secretion, hence the shrinkage of the contents. But 

 since the end-products of digestion are being absorbed also, 

 there is no tendency toward extreme concentration. In 

 the large intestine there is but little secretion, and the con- 

 tinuation of the absorption of water reduces the contents 

 at last to a nearly solid consistency. 



The colon appears to be of very unequal value to animals 

 of different classes. In the carnivora the work of diges- 

 tion and absorption is so nearly finished by the small in- 

 testine that very little remains to be done. The small 

 quantity of matter having a potential food value may be 

 accompanied into the large intestine by enzymes, which 

 may there carry further their digestive action. Such food, 

 however, is likely to be a negligible amount, and the digest- 

 ive powers of the mixture at this point are unreliable. 

 In the herbivora, the food being bulky and refractory, 

 a considerable portion may arrive undigested in the colon. 

 These animals have very capacious ceca, in which great 

 masses of contents seem to be held for long intervals. 

 The digestion occurring there may be partly effected by 

 the native secretions, but it is believed to be largely the 

 work of bacteria. 



The average human being resembles the carnivorous 

 type rather than the other. Numerous cases have been 

 observed in which no use was made of the colon, and it was 

 never difficult to maintain nutrition. When the large in- 



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