DIGESTION OF LAEGE INTESTINE. 341 



concluded. The peculiar odour, moreover, which is 

 acquired after a short time by the contents of the large 

 bowel, would seem to indicate the addition to them, in 

 this region, of some special matter, probably excretory. 

 The acid reaction, which had become less and less distinct 

 in the small bowel, again becomes very manifest in the 

 caecum probably from acid fermentation processes in some 

 of the materials of the food. 



There seems no reason, however, to conclude that any 

 special, ' secondary,' digestive process occurs in the caecum 

 or in any other part of the large intestine. Probably any 

 constituent of the food which has escaped digestion and 

 absorption in the small bowel may be digested in the large 

 intestine ; and the power of this part of the intestinal 

 canal to digest fatty, albuminous, or other matters, may 

 be gathered from the good effects of nutrient enemata, so 

 frequently given when from any cause there is difficulty in 

 introducing food into the stomach. In ordinary healthy 

 digestion, however, the changes which ensue in the chyme 

 after its passage into the large intestine, are mainly the 

 absorption of the more liquid parts, and the addition of 

 the special excretory products which give it the charac- 

 teristic odour. At the same time, as before said, it is 

 probable that a certain quantity of nutrient matter always 

 escapes digestion in the small intestine, and that this 

 happens more especially when food has been taken in 

 excess, or when it is of such a kind as to be difficult of 

 digestion. Under these circumstances there is no doubt 

 that such changes as were proceeding in it at the lower 

 part of the ileum may go on unchecked in the large bowel, 

 the process being assisted by the secretion of the nume- 

 rous tubular glands therein present. 



By these means the contents of the large intestine, as 

 they proceed towards the rectum, become more and more 

 solid, and losing their more liquid and nutrient parts, 

 gradually acquire the odour and consistence characteristic 



