VIIL] THE INFECTIVENESS OF CHOLERA. 143 



of distinction to be drawn between cholera and other in- 

 fectious diseases. Other infectious diseases, such as typhus, 

 typhoid fever and relapsing fever, also attack with predilec- 

 tion the poor, ill-nourished, and weak ; other infections 

 spread by filth and uncleanliness of person, of air and water, 

 but just as in these, so also in cholera, a healthy state of 

 the intestine does not ensure immunity against infection. 



It will probably be argued that once the comma-bacilli 

 have settled in the small intestine and multiplied, the fact 

 will not be disputed that they can produce a chemical poison 

 which by absorption produces the symptoms of cholera, and 

 that this at least can be inferred from the experiments on 

 animals ; and it will be further argued that this is exactly 

 what Koch maintains. In other words, owing to the 

 absence of comma-bacilli from the blood and the tissues, 

 and owing to their presence in the alimentary canal only, it 

 must be assumed that they produce there a chemical fer- 

 ment which being absorbed produces cholera, and such an 

 inference is supported by the positive experiments on 

 animals. While admitting that the comma-bacilli, like 

 some other saprophytic bacteria, are under certain 

 favourable conditions of growth capable of producing a 

 chemical ferment analogous to ptomaines, I do not admit 

 that this is applicable to cholera. Certain important con- 

 siderations previously mentioned, for example, that the 

 comma-bacilli can only multiply in an intestine previously 

 diseased, offer an unsurmountable primary difficulty to this 

 assumption ; moreover, there is the fact that the comma- 

 bacilli pass only with great difficulty unscathed through the 

 normal stomach, or through a stomach in which the contents 

 are always acid or perhaps of more than normal acidity as 

 in many cases of dyspepsia ; whence it would follow that 

 the number of persons subject to cholera ought to be quite 



