76 BACILLUS DIPHTHERIA 



animals when injected into their tissues. The pro- 

 tection so secured is valid against either the virulent 

 organism or the poisons produced by the organism. 

 This protective or " anti-toxic " serum also possesses 

 therapeutic properties, and secures the recovery of 

 animals already infected. It is this serum which is 

 so largely used in the treatment of diphtheria in 

 man. 



