Immunity of the skin and mucous membranes 419 



sensitive to the destructive action of the gastric juice of man, of the 

 dog, and of the sheep, is, from the experiments of Straus and Wurz, 

 quite capable of passing through the stomach without being affected. 

 Stern 1 , as the result of his own researches, as well as of those of his 

 pupils, came to the conclusion that this micro-organism is not in the 

 least affected by the gastric juice of a healthy man, containing the 

 normal amount of hydrochloric acid. It was only in cases of hyper- 

 secretion and of hyperacidity that the micro-organisms of typhoid fever 

 were destroyed before they reached the small intestine. 



The cholera vibrio also can pass through the stomach and its acid 

 juice. After Koch's demonstration of the great susceptibility of this 

 organism to acids in vitro, it was generally concluded that it must 

 perish in the normal content of the stomach. Many cases have 

 since been recorded in which the cholera vibrio was found, in times 

 of cholera epidemics, in the faeces of healthy persons. In order 

 to get into the large intestine it had to pass through the normal 

 stomach. In experimental cholera in young suckling rabbits, a large 

 number of vibrios were also found in the distinctly acid contents 

 of the stomach, and they were seen to pass into the small intestine 

 without any neutralisation of the acidity of the stomach taking place. 

 This example proves, once again, that the phenomena that occur 

 within the living body cannot be identified with those that go on in 

 the test-tube, in vitro. 



Whilst the acidity of the gastric juice exerts a certain influence on [440] 

 micro-organisms, the pepsin which it contains acts unfavourably on 

 their toxins. There are many poisons which are readily absorbed, 

 without being modified, by the mucous membrane of the stomach. 

 Even the venom of snakes can, under certain conditions, produce 

 its toxic effect as it is absorbed through the stomach. Thus, ac- 

 cording to the experiments of Wehrmann 2 , pepsin exerts a very 

 feeble action on this poison. On the other hand, this diastase has 

 a marked action on certain bacterial toxins. Gamaleia 3 pointed out 

 that pepsin destroys the diphtheria toxin. Charrin and Lefevre 4 

 have shown that it also weakens other microbial toxins. According 

 to Nencki and Mmes Sieber and Schoumow-Simanowski 6 , the gastric 



1 Von Volkmann's Samml. klin. Vortr., Leipzig, 1898, no. 38, S. 290. 



2 Ann. de FInst. Pasteur, Paris, 1898, t. xn, p. 510. 



3 Compt. rend. Soc. de biol., Paris, 1892, p. 153. 



4 Compt. rend. Soc. de biol., Paris, 1897, p. 830, and Charrin, "Les defenses 

 naturelles de Porganisme," Paris, 1898, p. 128. 



5 Centralbl.f. Bakteriol. u. Parasitenk., Jena, 1898, Bd. xxni, SS. 840, 880. 



272 



