INFECTION AND IMMUNITY. 403 



others had demonstrated that a sort of immunity 

 against certain forms of infection may be afforded to 

 susceptible animals by the injection into their tissues of 

 the products of growth of particular organisms which, 

 if themselves introduced into the animal body would 

 produce fatal results. In the light of subsequent experi- 

 ments, however, the interpretation of this phenomenon 

 is not that claimed by the supporters of this hypothesis. 



As opposed to the view of Chauveau, Pasteur' and 

 certain of his pupils believed that the immunity fre- 

 quently afforded to the tissues by an attaclv of infection, 

 or following upon vaccination against infection, was 

 due rather to an abstraction from the tissues, by the 

 organisms that were concerned in the primary attack, 

 of a something that is necessary to the growth of the 

 infecting organism should it gain entrance to the body 

 at any subsequent time. This view is known as the 

 exhaustion hypothesis. 



As to the exhaustion hypothesis of Pasteur, there is, 

 as yet, no evidence whatever for its support. The 

 work of Bitter,^ which was undertaken with the view 

 of determining if, in the process of acquiring immunity, 

 there occurred this exhaustion from the tissues of 

 material necessary to the growth of bacteria that might 

 gain entrance to them at some later date, gave only 

 negative results. The flesh of animals in which im- 

 munity had beeu produced contained all the elements 

 necessary for the growth and nutrition of the bacteria 

 against which the animals had been protected, just as 

 did the flesh of non-vaccinated animals. 



In 1884 Metchnikoff ' published the first of a series 



1 Bull, de I'Acad. de Med., 1880. 2 Zeitschr. fur Hygiene, Bd.iv., 1888. 



2 Arbeilen aus dem ZoSlogischen Institut der Dniversitst Wien., 1884, Bd. v. 

 Fortschritte der Med., Bd. ii., 1884. 



