Chapter X 



THE RELATION OF CYTOST TO 

 BACTERIAL INFECTION 



The relation between bacterial invasion and cytost 

 may be viewed from three different aspects: the re- 

 lease of cytost as a result of injury caused by bacterial 

 infection ; the cumulative effects of bacteria and cytost 

 acting together; and the relationship between cytost 

 immunity and bacterial immunity. At the outset we 

 should expect that any microorganism capable of ef- 

 fecting the destruction of the tissues of a higher ani- 

 mal would bring about the production of cytost in 

 much the same fashion as would any other means of 

 injury. In consequence, the infected animal should 

 exhibit symptoms of cytost intoxication as well as 

 those due to the bacterial toxins per se. 



When subtlethal quantities of exocellular bacterial 

 toxins, such as diphtheria toxin, are injected into the 

 skin of an animal, a local reaction sets in after the 

 lapse of several hours. The reaction usually com- 

 mences as a slight reddening at the site of injection, 

 indicating a localized capillary dilatation. This is fol- 

 lowed by a localized edema, which is due to an in- 

 creased permeability of the capillaries. Since, as we 

 have seen, both these effects are caused by cytost, and 



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