164 



ANAPHYLAXIS IN ITS RELATION TO DISEASE 



takes place, and becomes, in turn, to a certain extent at least, respon- 

 sible for the more or less continuous symptomatic evidence of disease. 

 If the number of organisms is small, or if they have been attenu- 

 ated by artificial means, the incubation period is much longer. In 

 such an event the antibody production begins in the third week, 

 but it is not until the fifth week that a sufficient quantity of 

 anaphylatoxin is formed to elicit manifest symptoms (Fig. 7). 



Fia. 6 



15 



Threshold of Death- 



Injection of virulent 

 | tuberclebacilli 



Manifestations of Disease 



Diagram illustrating the interaction between antigen and antibody in a fatal case of cattle 

 tuberculosis, following the injection of a moderate dose of tubercle bacilli. (Taken from v. Pirquet.) 



Threshold of clinical evidence of d 



.. Clinical 



Symptoms 



Diagram illustrating a protracted period of incubation in its relation to the interaction between 

 tubercular antigen and the corresponding antibody; infection having been produced by the admin- 

 istration of tubercle bacilli in small number or in attenuated condition. (Taken from v. Pirquet.) 



The subsequent course of the infection will, of course, depend 

 upon circumstances. If recovery takes place the further multipli- 

 cation of tubercle bacilli ceases; the foci that are already in exist- 

 ence are encapsulated and the active clinical symptoms disappear. 



