354 PHYSIOLOGY CHAP. 



carefully, in order to restrict the action of the bacteria and cocci 

 which develop to such an enormous extent with the method of 

 the intestinal ring. Even under these conditions, in which the 

 intestine was not abnormally excited, he found that a slight 

 epithelial regeneration took place, but he concluded that a large 

 proportion of the excrements must under all circumstances 

 be formed, according to Hermann's original opinion, from the 

 excretory products of the intestinal mucosa. 



Fritz Voit (1892) supported the same conclusion. He observed 

 that in a short isolated tract of intestine (35 cm. long) it was 

 possible in 3 weeks to obtain 14-20 grins, faeces (about 0'6-TO 

 grm. per diem). 



We can hardly suppose that the chief part of such a large 

 mass can consist of shed and disintegrated epithelium. It 

 represents, indeed, about f the amount of epidermis and hair 

 which the dog (according to C. Voit) loses daily from the entire 

 surface of the cutis. On the other hand, this conspicuous loss of 

 substance from the bowel is readily explained on the assumption 

 that it depends essentially upon secretory processes, and that 

 epithelial desquamation plays a minor part. 



In a careful series of new and more minute researches and 

 comparisons Fr. Voit confirms the fundamental facts put forward 

 by C. Voit, Fr. Miiller, and Hermann, i.e. that in an ordinary diet 

 without excess of nitrogen, a considerable part of the faeces, and 

 on a flesh diet almost the whole mass, consists of the same 

 excretory products as are poured out in fasting, and are to a 

 certain extent increased with alimentation. 



The larger digestive glands, i.e. the liver and the pancreas, take 

 hardly any part in the formation of the faeces. C. Voit in fact 

 found that in dogs with a fistula of the gall-bladder, the flesh or 

 mixed diet daily results in almost the same amount of faeces as 

 appeared on the same diet before the fistula was established, 

 showing that the bile is almost entirely reabsorbed, and takes only 

 a small share in the formation of the faeces. 



Fr. Voit's work shows that the formation of faeces is a 

 physiological function almost exclusively confined to the small 

 intestine. On comparing the faeces formed in a short isolated 

 segment of intestine with those formed in the remainder of the 

 bowel in the same dog, he found that approximately the same 

 amount of faeces was obtained per unit of intestinal surface, which 

 leads one to suppose that not only the bile, but also the pancreatic, 

 gastric, and salivary secretions are for the most part reabsorbed. 

 The intestine, besides its digestive and absorbing functions, has 

 thus an excretory function, i.e. it is one of the channels by which 

 the waste products of the body are eliminated. That this last 

 function is of no little importance may be gathered from the fact 

 that a dog of 30 kilos, body-weight is capable, during starvation, of 



