A GENERAL RESUME OF IMMUNITY. 529 



which has not been appreciated, have been confirmed and re-studied 

 now that there is a generalizing acceptance of the value of phagocytic 

 defense. And this is particularly the case with the numerous facts 

 which we owe to Metchnikoff. Such is the case also with certain 

 of the facts that have been mentioned in various articles of this 

 volume, particularly as regards negative chemiotaxis, the phenom- 

 enon of adaptation which bacteria employ to protect themselves 

 against phagocytosis, and the visible index of which consists in the 

 appearance of a capsule, the manner in which leucocytes act with 

 certain poisons, toxins, or alkaloids like quinine, and the like. The 

 fundamental importance of phagocytosis is to-day universally ad- 

 mitted and is moreover evidenced by the large number of articles 

 which deal with means of computing the intensity of this phenom- 

 enon in normal, infected, or immunized animals. 



