BACTERIAL POISONS 33 



ing life, and given up to the surrounding media only after death 

 and disintegration of the cells. 



Pfeiffer 14 was the first one to formulate this conception in his 

 studies upon cholera poisons. He found that when cholera spirilla 

 were grown upon broth and filtered after 6 or 7 days, the filtrate was 

 but slightly toxic, but that, in this case, unlike the conditions pre- 

 vailing in diphtheria and tetanus cultures, the residue of bacterial 

 cell bodies, even after they had been killed by chloroform, thymol, 

 or drying, were powerfully poisonous. 



We have then two main classes of specific bacterial poisons. One 

 typified by diphtheria and tetanus poisons is produced during 

 the period of energetic growth by the living bacteria, is given off to 

 the surrounding culture fluid as a secretion or excretion, and can be 

 obtained in bacteria-free filtrates at a time when few, if any, of the 

 micro-organisms have died or disintegrated. These are spoken of as 

 "true toxins" or "exotoxins." 



The other group typified by the cholera poisons as described by 

 Pfeiffer is apparently an intracellular, constituent part of the bac- 

 terial body not given off during life and not, therefore, obtained in 

 filtrates of young living cultures. If the cultures are preserved until 

 cell death has taken place and the dead bodies have been extracted 

 by the culture fluid, the filtrate becomes gradually more toxic. The 

 bodies of such bacteria are in themselves powerfully toxic when 

 injected, dead or alive. These poisons for obvious reasons Pfeiffer 

 has named the "endotoxins" since he regarded them as specific and 

 definite substances, present as such in the living bacterial cell. 



In addition to the endotoxins the bacterial protein contains sub- 

 stances which attract and lead to the accumulation of leukocytes. In 

 other words, they exert a positive chemotactic influence. This was 

 first observed in 1884 by Leber, 15 who induced the formation of pus 

 by injecting dead staphylococcus cultures, and, later, found that the 

 same effect resulted from the injection of alcoholic extracts of 

 staphylococci. These chemotaxis-inducing substances were later 

 particularly studied by Buchner. Buchner 16 extracted them from 

 many varieties of bacteria, independent of pathogenicity. Although 

 there are quantitative differences, all bacteria seem to contain such 

 substances, and Buchner believed the chemotactic property to be a 

 general attribute of the bacterial protoplasm. He speaks of his ex- 

 tracts as bacterial proteins. 



The true toxins or exotoxins,, then, appear to be products of liv- 

 ing bacteria given off from these very much as are the ferments and 

 enzymes by which micro-organisms cause cleavage of carbohydrates 

 or proteins and indeed the French school, from the first, compared 



14 Pfeiffer. Zeitschr f. Hyg., Vol. II, 1892. 



15 Leber. "tiber die Entziindung," Leipzig, 1884. 



16 Buchner. Berl. klin. Woch., 1890. 



