IMMUNITY. 389 



munity. The common feature in all cases of 

 immunity of this sort is the formation of active 

 bodies in the serum of the immunized animals 

 by means of the stimulus exerted by the 

 poison that is introduced, and it is the action 

 of these active bodies upon the active poison 

 that causes the molecular movement of the lat- 

 ter to cease. Sometimes the specific, isopathic 

 stimulus of the same nature is best adapted for 

 thus rendering active the body-proteid, and 

 hence is in a sense necessary, but sometimes 

 a heterogeneous and specifically dissimilar, or 

 even an entirely foreign stimulus is sufficient. 

 Although the results of the experiments 

 upon man are still in dispute the results ob- 

 tained by experiments upon animals with 

 specifically different bacteria, metabolic pro- 

 ducts, proteids and sera are frequently just as 

 favorable as the results obtained by isopathic 

 and homeopathic treatment with specifically 

 identical or closely similar material. 



For protective inoculation and healing, ac- 

 cordingly, isopathy or the use of specific dis- 

 ease germs and their metabolic products is not 

 essential; the same results can be reached 

 with other bacteria. But probably it is not 

 essential that bacteria or bacterial products 

 be employed for this purpose. In experiments 

 upon animals I succeeded in the case of two 



