26 PRODUCTS OF BACTERIAL ENERGY 



organisms themselves. For example tuberculin, wholly free from 

 tubercle bacilli, will produce a reddening of the skin or a rise of 

 temperature if injected into a tuberculous individual. The reac- 

 tions from mallein and luetin (q.v.) injection are due to toxic pro- 

 teiris^ They are thermostable, that is not destroyed at 100 C. 

 TKfsis also called coctostabile. 



In practice it may not be so simple to separate bacteria that 

 produce the various poisonous elements as the above descriptions 

 would indicate. Toxins are all in a sense specific. That is they 

 are for the most part selective in action. The diphtheria toxin is 

 absorbed from a raw inflamed surface under cover of an exudate 

 composed of fibrin and bacteria. The tetanus toxin is absorbed 

 from its seat of manufacture in the depths of a punctured wound. 

 They are harmless if swallowed. The endotoxin of typhoid bacilli 

 has no pathogenic effect if swallowed or rubbed in skin or mucous 

 membrane. If it be injected under the skin in the absence of 

 bacteria it will call forth reactions on the part of the body similar 

 to those expressed when living typhoid germs are circulating. 

 Toxins are again relative in their affinities. Tetanus toxin is fatal 

 for man and horses while rats and birds are resistant to it. We 

 use this expression of specificity for determiding the nature of 

 certain germs. We may speak of these failures to react as fail- 

 ures of receptivity on the part both of the microbe and the injected 

 animal. 



