ABSORPTION 291 



absorption of water from the stomach of any animal. There is 

 very little absorption of this fluid from the small intestines, 

 whereas in all animals the large intestines are the chief seats of 

 absorption. In the horse the caecum, in other animals the large 

 colon is the chief seat. 



In the matter of the absorption of salts, a good object-lesson 

 of the peculiar selective powers of the epithelial cells is obtained. 

 Chlorides are readily taken up, but sulphates only with difficulty ; 

 iron is taken up, but its near ally, manganese, is absorbed with 

 difficulty. Though these facts suggest that the process is one of 

 secretion rather than the result of physical action, yet it is im- 

 possible to neglect physical factors as playing a part. Finally. 

 Colin's experiments on the herbivora snowed that absorption of 

 salts, such as prussiate of potash, iodide of potassium, tartar 

 emetic, and many other substances and colouring matters such as 

 chlorophyll, occurred by the chyle vessels, though not necessarily 

 exclusively. 



Much of the foregoing refers to absorption from the small 

 intestine, but it would be wrong if we failed to emphasise the 

 fact that in the herbivora especially the large intestine is the 

 seat of vitally important digestive processes. An attempt has 

 been made (p. 220) to deal with these in the light of our limited 

 knowledge, but it is a very imperfect picture. It is only referred 

 to here in order to emphasise the fact that the large intestines, 

 though they present no villi and no secretion other than the 

 succus entericus, are important seats of digestion and absorption. 

 A man may manage to get along without his large intestines, 

 the horse could manage if he had half the present length of small 

 intestine, but he could not afford to spare an inch from his large 

 bowels. From imperfect knowledge, and the difficulties attached 

 to experimental inquiry in the larger animals, we do not know 

 the absorptive function of any portion of the large intestine 

 excepting the bare fact that it does absorb. At p. 219 attention 

 is drawn to the remarkable fact that a few inches in the intestines 

 of the horse separate fluid faeces from solid faeces. Who can 

 doubt the important changes which must be taking place in those 

 few inches ? The ox and sheep are in their anatomical arrange- 

 ment very similar — almost identical, in fact. Their diet is 

 identical, perhaps their digestive processes identical, up to a 

 certain point ; then they differ widely : the faeces of the sheep 

 are firm and dry, those of the ox soft and unformed. There 

 must be important differences in the intestinal absorption of 

 animals so nearly related. 



