THEORIES OF IMMUNITY. 



specific for each reaction in which it occurs; one 

 for typhoid, one for diphtheria, and so on. 



They do not yet agree, however, that T com- 

 plement" (alexine) is multiple. One side main- 

 tains that it is the same for all reactions, the 

 other that it differs and is specific for each. 



The point that has been insisted upon by 

 Metchnikoff from the beginning is maintained: 

 that in all reactions the cell activity must inter- 

 vene at some stage of its production. 



101 



