252 INTESTINAL SECRETIONS. 



soluble substances, and thus facilitate absorption. The 

 alkalinity of the contents of the intestines increases near the 

 coecum, and certain principles in the food are digested, espe- 

 cially the starchy principles. It would appear, that when the 

 gastric digestion is very active,, the intestinal contents are 

 less decidedly alkaline, but the alkalinity is very marked 

 when the acid secretion within the stomach has been scanty, 

 and digestion is chiefly carried on in the intestinal tube. 



The fluidity of the contents of the small intestine is in part 

 due to the abundant secretions which are mixed with the 

 food, after it has passed through the stomach, but also to the 

 rapid onward passage of indigestible matters which accumu- 

 late in the large intestine. The process of solution and dilu- 

 tion to which the alimentary matters are subjected in the 

 small intestine, are very favourable to the absorption which 

 we shall hereafter fully consider. The first portion of the large 

 intestine or blind head of the colon coecum caput coli is 

 distended with very fluid contents, and in the horse this 

 organ has been spoken of by slaughterers and others as 

 a second stomach. It retains liquids which pass rapidly 

 through the small intestine for some time, and they get gra- 

 dually absorbed. 



The solid mass, which moves slowly towards the anus be- 

 coming harder and drier, contains: Istly, all indigestible 

 materials, and especially in vegetable feeders, food protected 

 by a cuticular envelope, and which may have escaped masti- 

 cation; 2ndly, digestible materials which have escaped solu- 

 tion and absorption ; 3rdly, epithelium and residue of secre- 

 tions discharged in abundance by the mucous surface of the 

 intestine and glands before-mentioned. Mr Sibson says: 



" The solid excrements consist of those portions of the 

 food unfit for assimilation, consisting for the most part of 

 woody fibre, as well as of other insoluble materials of the 



