222 THE ACTION OF THE LIVING CELL 



specific microorganism, while in others no micro- 

 organism appears to be concerned. In the first instance, 

 it is known that a number of unrelated microorgan- 

 isms may give rise to the same type of pathology. 

 This of course indicates that the particular patholo- 

 gies observed in such instances are due, not to the 

 specific activities of the microorganisms concerned, 

 but to a common factor resident within the host. 



Such considerations suggested to the writer that 

 cytost might be this common factor. With this in 

 mind, experiments have been conducted towards this 

 end, and it has been found that several so-called non- 

 specific diseases may be simulated in animals by the 

 injection of cytost. These experiments, which have 

 been discussed elsewhere (see Chapter XIII), will 

 not be treated of here, since they are not of general in- 

 terest. In this connection, however, it should be noted 

 that the role played by the non-specific organisms fre- 

 quently associated with such diseases is probably akin 

 to that of B. coli in the experiments described earlier 

 in the chapter: that of an adsorbant which intensifies 

 the action of cytost. 



So far we have considered the relation of bacterial 

 infection to cytost only from the standpoint of cytost 

 formation and intoxication. Passing now to a con- 

 sideration of the possible relationship between im- 

 munity to cytost and to disease, it is at once apparent 

 that in the case of infection by proteolytic micro- 

 organisms which can liberate cytost, the degree of 

 an animal's immunity to cytost will be a determining 

 factor of some importance in his offensive against the 

 invading bacteria. If, then, we consider all members 

 of a given population to have equal chances of infec- 



