IMMUNITY. 341 



substances merely furnish, the necessary stim- 

 ulus. The peculiar antitoxic and bactericidal 

 action observed in such cases is due to the 

 qualities of the substances which are formed in 

 the serum in larger quantities in those animals 

 made immune or tolerant of poison ; normal 

 animals already contain the same " specific " 

 substances but in smaller quantities.' The 

 property of specificity which is seemingly a 

 newly-acquired quality, may not unreasonably 

 be conceived of as a quantitative variation and 

 as dependent upon the bringing into action of 

 normal forces by appropriate stimuli. 



The formation of antitoxin is certainly noth- 

 ing but an accessory or concomitant to arti- 

 ficial immunity and habituation to poison, and, 

 since it is not necessary for the acquisition of 

 these properties, it is not their cause. 



Before we discuss the consequences of this 

 fact let us consider another side of protective 

 inoculation in general. 



Anticipatory Inoculations Specific Curative 

 Inoculations Specific Serum Therapy. 



In considering Brehmer's method for the 

 cure of tuberculosis, I have already mentioned 

 that the same remedies which nature employs 

 to convert a predisposition toward disease into 



