FACTORS OF PATHOGENIOITY AND INFECTION 2,37 



substances, called by Pfeiffer endotoxins, do not produce antitoxins. 

 It is doubtful, in our minds, whether they may be regarded as 

 strictly specific in all cases. 



In addition to these poisonous substances, the writer, with Kutt- 

 ner and Parker, 3 has recently obtained non-specific toxic substances 

 for a great many different bacteria (streptococci, typhoid bacilli, 

 influenza bacilli, etc.) which appeared in cultures as early as 6 to 18 

 hours, could be obtained by filtration, and could also be obtained 

 by washing young cultures on solid media with salt solution and 

 filtering. These substances are not unlikely similar to those en- 

 countered by some other writers who have interpreted them as true 

 exotoxins, but, as far as we can determine, they are neither specific 

 nor antigenic. Nevertheless, they are regular in appearance, suffi- 

 ciently potent to make rabbits very sick, though rarely to kill them, 

 and must be taken into account in all work in which the toxic 

 substances of bacteria are studied by the usual methods. We can 

 speak of them, for want of more accurate definition, as bacterial 

 "X" substances. 



In resistance to chemical action and heat, the various poisons 

 show widely divergent properties. As a general rule, most true 

 soluble toxins are delicately thermolabile, they are destroyed by 

 moderate heating, and deteriorate easily on standing. Their chemical 

 nature is by no means clear, but, on precipitation of toxic solutions 

 with magnesium sulphate, these poisons come down together with 

 the globulins. The nature of the "endotoxins" is still less clearly 

 understood. Most of them are far less liabile than the extracellular 

 poisons. Some powerful intracellular poisons, like those of the 

 Gartner bacillus of meat poisoning and the poison attached to the 

 bodies of typhoid bacilli may undergo exposure to even 100 C. and 

 still retain their toxic properties. The nature of each individual 

 poison will be discussed in connection with its microorganism. 



It should be remembered, moreover, by those studying bacterial 

 poisons that recent investigations have shown that a number of 

 bacteria (coli, influenza, etc.) may produce substances either identical 

 with or closely related to histamin and tyramin, on pepton media, 

 after five or more days of growth. 



9 7insftcr, Parker and Kuttner, Transact. Soc. for Exp. Biol. and Mod., Jan., 

 1921. 



