ANTITOXINS 21 



produce dissolved poisons in the culture fluid. 

 These poisons are neither ptomaines nor proteid 

 substances; their chemical nature is still absolutely 

 unknown. They are extremely sensitive to exter- 

 nal influences, especially against heat, and in many 

 ways are very analogous to ferments. Physio- 

 logically the toxins are extremely poisonous, far 

 beyond that of any of the ordinary' well known 

 poisons, and this poisonous action manifests itself 

 only after a certain latent period known as the 

 period of incubation. Finally one of the funda- 

 mental properties of the toxins is their ability 

 to excite, in the organism attacked, antitoxins 

 directed specifically against them, so that for every 

 true toxin there is a corresponding antitoxin. 



In addition to these bacterial toxins we know 

 of other poisonous substances possessing similar 

 characteristics. Among these are the " zootoxins," 

 - snake venoms, spider and toad poisons, the 

 toxin of eel blood, and the " phytotoxins," 

 ricin, crotin, abrin, etc. It may be mentioned that 

 some of these are of somewhat more complex con- 

 stitution than the ordinary bacterial toxins. Ricin, 

 for example, appears to possess one haptophore 

 group but two ergophore groups, a toxic and an 

 agglutinating one. In the case of the snake 

 venoms it is not yet definitely known whether 

 they are haptins of the first order or of the 

 second. (See page 49.) 



