158 



ANAPHYLAXIS IN ITS RELATION TO DISEASE 



thus coexist, a more or less continuous formation of anaphylatoxin 

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

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



FIG. 6 



Day s.l 



15 



Threshold of Death ^t ~ 



Injection of virulent 

 I tubercle bacilli 



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.) 



FIG. 7 



2!) 



Threshold of clinical evidence of disease h 



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 administration of tubercle bacilli in small number or in attenuated condition. (Taken 

 from v. Pirquet.) 



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 anaphy- 

 'latoxin is formed to elicit manifest symptoms (Fig. 7). 



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

 upon circumstances. If recovery takes place the further multi- 

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



