340 DIGESTION. 



blood, the latter would be too much drained, were it not 

 that the same fluid after secretion is again re-absorbed 

 into the current of blood going into the blood charged 

 with nutrient products of digestion coming out again by 

 secretion through the glands in a comparatively uncharged 

 condition. 



It has been said before that the contents of the stomach 

 during gastric digestion have a strongly acid reaction. 

 On the entrance of the chyme into the small intestine, 

 this is gradually neutralized to a greater or less degree by 

 admixture with the bile and other secretions with which 

 it is mixed, and the acid reaction becomes less and less 

 strongly marked as the chyme passes along the canal 

 towards the ileo-csecal valve. 



Thus, all the materials of the food are acted on in the 

 small intestine, and a great portion of the nutrient matter 

 is absorbed the fat chiefly by the lacteals, the other 

 principles, when in a state of solution, chiefly by the blood- 

 vessels, but neither, probably, exclusively by one set of 

 vessels. At the lower end of the small intestine, the chyme, 

 still thin and pultaceous, is of a light yellow colour, and 

 has a distinctly faecal odour. In this state it passes 

 through the ileo-csecal opening into the large intestine. 



Summary of the Process of Digestion in the Large Intestine. 



The changes which take place in the chyme after its 

 passage from the small into the large intestine are probably 

 only the continuation of the same changes that occur in 

 the course of the food's passage through the upper part of 

 the intestinal canal. From the absence of villi, however, 

 we may conclude that absorption, especially of fatty 

 matter, is in great part completed in the small intestine, 

 while, from the still half-liquid, pultaceous consistence of 

 the chyme when it first enters the csecum, there can be no 

 doubt that the absorption of liquid is not by any means 



