318 BACTERIA IN INFECTIOUS DISEASES. 



gin which has been proved to depend upon 

 the presence of bacterial organisms, has led many 

 physicians confidently to anticipate that a malarial 

 germ would be found in the bodies of those suffer- 

 ing from malarial poisoning ; and since the demon- 

 stration of the anthrax bacillus, and the spirillum 

 of relapsing fever, it seems to have been rather 

 hastily assumed that all disease germs are to be 

 sought especially in the blood. In intermittent 

 fever, however, it would seem, a priori, that the 

 hypothetical parasite would not be likely to find a 

 suitable culture-medium in the blood of a living 

 animal ; (a) because its normal habitat is in 

 swamps, where its development is associated with 

 the decomposition of vegetable matter ; and 

 () because, so far as we know, parasitic micro- 

 organisms, which multiply freely in the blood of 

 living animals, produce infectious diseases com- 

 municable from one individual to another, whereas 

 we have no evidence that this ever occurs in the 

 paludal fevers. Conditions more nearly approach- 

 ing those which favor the development of the 

 poison external to the body may, however, be 

 found in the alimentary canal, and we may sup- 

 pose that the germ locates itself here. Or we 

 may admit the possibility that its action is re- 

 stricted to the production of a volatile chemical 

 poison which is evolved as a result of its vital 

 activity in the localities where it abounds external 

 to the body; and that this infects the atmosphere 

 in the vicinity, and produces malarial poisoning in 



