580 BA CTERIOLOG Y. 



Nuttall), Fodor, Hankin, Pfeiffer, Ehrlich, Behring, 

 Roux, and a host of others whose names are more or 

 less prominent in current literature. In the following 

 pages we will present and discuss certain results of 

 investigations that serve both to mark the evolutionary 

 progress of our knowledge and to elucidate the more 

 important features of this complicated subject, 



THE RETENTION HYPOTHESIS OF CHAUVEAU. In 

 1880 Chauveau 1 suggested an explanation for the 

 phenomenon of immunity that has since been known as 

 the " retention hypothesis" It is, in short, as follows : 

 that the immunity commonly seen to exist in animals 

 that have passed through an attack of infection from 

 a subsequent outbreak of the same malady, and likewise 

 the immunity that has been produced artificially by 

 vaccination, exist by virtue of some bacterial product 

 that has been retained or deposited in the tissues of those 

 animals, and that this product by its presence prevents 

 the development of the same organisms if they should 

 subsequently gain access to the body. 



Bearing upon this view the experiments of Sirotinin, 2 

 made with cultures of various pathogenic bacteria, 

 demonstrated that, in so far as culture-experiments were 

 concerned, the only substance produced by growing 

 bacteria that could be in any way inimical to their further 

 development were substances that gave rise to altera- 

 tions in the reaction of the medium in which they were 

 developing i. e., acids or alkalies produced by the bac- 

 teria themselves. So long as the organisms were not 

 actually dead from exposure to these substances correc- ' 

 tion of the abnormal reaction was followed by further 

 development of the organisms. Sirotinin also states 



1 Comptes rendus, etc., July, 1880, No. 91. 



2 Zeitschrift fur Hygiene, 1888, Bd. iv. 



