422 Chapter XIII 



substance which is powerfully bactericidal. In reality, neither one 

 nor the other of these suppositions receives any confirmation. The 

 intestines of the two Invertebrata I have named are very poor in 

 micro-organisms and their contents do not exhibit the slightest 

 bactericidal power. When a little of their contents is placed in 

 tubes and kept at a suitable temperature it is not long before it 

 becomes filled by a great number of bacteria of various kinds. 



To explain this poverty of the microbian flora of the intestines in 

 these examples we must postulate some kind of mechanical purifi- 

 cation, facilitated by the peristaltic movements of the digestive canal. 

 Even in animals which have an abundance of micro-organisms 

 in the small intestine, there must be produced some phenomenon 

 which brings about the disappearance of a certain number of them. 

 In mammals the small intestine always contains far fewer micro- 

 organisms than does the large intestine ; in birds, the coecum is much 

 richer in bacteria than is the rest of the digestive canal. Schiitz 1 has 

 attempted to demonstrate the disinfecting power of the small intestine 

 in the dog by feeding it on substances to which he had added a large 

 number of Gamaleia's vibrio ( Vibrio metchnikovi). After convincing 

 himself that micro-organisms perish in the digestive canal and are 

 never found in the excrementa, Schiitz introduced into his dogs 

 [443] a cannula, one branch of which passed into the pylorus, the other 

 into the duodenum. By means of a small apparatus he could readily 

 interrupt the communication between the stomach and the intestine. 

 The vibrios, mixed with biscuit, and softened with water, introduced 

 directly into the duodenum (whilst the stomach was kept completely 

 isolated), penetrated into the large intestine in small numbers only. 

 The lower part of the colon, the rectum and the excrements gave no 

 cultures of vibrios and did not give rise to any growth except that of 

 the Bacillus coli. In this case the disinfection of the intestine took 

 place without any help from the gastric juice. Further, when Schiitz 

 killed dogs, after giving them food in which vibrios were mixed, these 

 organisms were found in the intestine only. The gastric acidity, 

 therefore, is not capable of killing these organisms, or of preventing 

 them from passing into the small intestine, in which, alone they were 

 killed. It was only with the aid of purgatives, such as castor-oil or 

 calomel, that Schiitz succeeded in preserving the vibrios in the intes- 

 tines and in finding them in the dejecta. This observer did not carry his 

 investigations further and did not make out the mechanism by which 

 1 Berl. klin. Wchnschr., 1900, S. 553. 



