DESCRIPTIONS OF PATHOGENIC BACTERIA. 187 



obtained from cultures by Hueppe, Scholl and 

 Petri. (Hueppe first obtained it from the bodies 

 of cholera patients in 1892, and Bosc likewise 

 found the poison in 1895 in the bodies of 

 cholera patients.) R. Pfeiffer has attempted to 

 identify the poisonous action of virulent comma 

 bacilli with the effect of their cell proteid, and 

 has accepted the theory of Cantani that it is not 

 the living comma bacilli which through their 

 formation of poison, are the effective agents, 

 but rather the dead comma bacteria by virtue of 

 the action of their poisonous body-substance. 

 The cholera toxin is not, however, identical with 

 the proteid of the bacterial cell ; the effect due 

 to the action of the latter substance is mani- 

 fested also by various forms of impotent comma 

 bacilli, but the toxin is formed only by the 

 virulent variety. 



The cholera bacteria grow in gelatin in the 

 form of colonies which appear like fine frag- 

 ments of glass or a tangle of glass threads ; 

 they liquefy the gelatin slowly. This initial 

 character of their growth in gelatin is tolerably 

 distinctive, yet many colonies grow rapidly, 

 others more slowly. In consequence of such 

 atypical growth, diagnosis is often quite diffi- 

 cult, and it is frequently necessary to postulate 

 the existence of varieties of the species. Cul- 

 tures obtained from an outbreak of cholera in 



