THEORIES OF IMMUNITY. 



Pasteur to the steps resulting in the practical 

 application of the laboratory results in such pro- 

 cedures as the protective inoculations against 

 anthrax and rabies. (See C. Renclus de 

 l'Academie des Sciences, 1880, T. XC, pp. 936, 

 952, 1030; T. XCL, pp. 571, 673.) 



The statement of the general principles was at 

 first met with much opposition and incredulity, 

 but was so overwhelmingly confirmed by other 

 observers that such incredulity soon disappeared. 



The first theory that was advanced to explain 

 the phenomena seen was that of Pasteur himself, 

 and was known as The Exhaustion Theory. In 

 accordance with this, the condition of immunity 

 following the injection of attenuated cultures of 

 a bacterium may be supposed to be due to the 

 exhaustion of certain elements in the tissues used 

 by the bacteria during their growth. These ele- 

 ments are not resupplied for some time by the 

 tissues, and during that time fresh bacteria en- 

 tering the tissues, finding the absence of some- 

 thing necessary for their growth, cannot grow, 

 and therefore no infection can take place. Such 

 a condition of things apparently exists in the test 



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