IMMUNITY AND SUSCEPTIBILITY. 13 1 



antitoxin was specific for its respective toxin and af- 

 forded protection against no other. This, however, 

 seems to be untrue, for while it is a fact that every anti- 

 toxin is more potent in its action upon that toxin whose 

 stimulation caused its formation, it is not infrequently 

 the case that it will incidentally but to a less degree pro- 

 tect against some others. Thus, quoting from Hueppe, 1 

 "Antitoxins that are formed specifically in serum act in 

 vitro upon poisons of a specifically different character in 

 the same manner as upon poisons specifically similar, 

 while the converse does not always obtain ; ' antivenin ' 

 annuls the poisonous effect of abrin, but not of diph- 

 theria toxin, tetanus toxin, or ricin ; antiabrin neutral- 

 izes the toxic effect of snake venom, diphtheria toxin, 

 and ricin, but not that of tetanus toxin ; tetanus anti- 

 toxin is antagonistic to snake venom, but powerless 

 against ricin and abrin ; rabies serum is potent against 

 snake venom, but impotent against the diphtheria and 

 tetanus toxins, and against ricin and abrin ; streptococ- 

 cus serum is potent against snake venom, powerless 

 against the others ; cholera serum is moderately effective 

 against snake venom, but without effect against the 

 others ; diphtheria antitoxin is powerless against snake 

 venom, tetanus toxin, ricin, and abrin ; the antitoxic 

 sera of swine erysipelas and typhoid are powerless against 

 all these poisons." 



Hueppe, Gottstein, and Schleich advanced the theory 

 that the specific action of the serums depended chiefly 

 upon the fact that "those particular specific organs, 

 tissues, cell territories, or cells which are involved in the 

 disease in question are stimulated." Wassermann closely 

 followed up this theory in the idea of toxin saturation 

 which forms the basis of his theory of immunity yet to 

 be described. 



Chemic Nature of Antitoxins. — The true nature of 

 antitoxins is unknown. They are stable substances 

 which are not destroyed by heat up to the point of coag- 



1 Principles of Bacteriology, translation by E. O. Jordan, 1899, p. 385. 



