﻿434 STRONG. 



and immunizing power emphasizes the fact that the more virulent 

 cholera organism produces the greater immunity, and MacFadyan 33 

 states that cholera cultures of high virulence yield the most toxic and 

 cultures of low viridence the least toxic juices, while in those instances 

 in which the virulence had heen allowed to diminish to such an extent 

 that 2 platinum loops of a culture did not kill a guinea pig, the toxicity 

 of the juices suffered a corresponding drop, 0.5 and even 1 cubic cen- 

 timeter failing to kill, whereas the animal succumbed to acute infection 

 from 0.1 cubic centimeter from a virulent culture. This led Mac- 

 Fadyan to conclude that virulence and toxicity were intimately related 

 as regards the cholera endotoxin, inasmuch as increased virulence implied 

 increased toxicity and vice versa. 



Therefore, in preparing our cholera prophylactic we select an organ- 

 ism which is known to possess high immunizing value and in addition 

 one of maximum virulence. 



THE SERUM TREATMENT OF CHOLERA. 



Recently the question of the serum treatment of cholera has again 

 attracted attention owing to the studies of Roux, Brau, and Denier, 

 Kraus and MacFadyan, and before entering into a discussion of the 

 subject I will briefly review their results. 



Brau and Denier 3J found that they were able to obtain a very active toxin 

 from the cholera vibrio by growing this organism in a special culture medium 

 consisting of bouillon Martin gelatine, 45 cubic centimeters, normal serum of 

 the horse 45 cubic centimeters, defibrinated blood 10 cubic centimeters, heated to 

 60° C. for three hours. By growth of the organism upon this medium they were 

 able to obtain the toxin regularly and in increased amount. After four days' 

 development the cultures had become liquified ; haemolysis occurred after twenty- 

 four hours; after seven days they were filtered through paper and then through 

 a Chamberlain F. candle. Certain precautions are necessary in order to obtain 

 the toxin in satisfactory amounts. They advise that the serum be heated at 

 60° C. for three hours in order to destroy the substances antagonistic to the 

 development of the cholera vibrio. The thermostat must be kept at a constant 

 temperature, variations even of 1° interfering with the production of the toxin; 

 the optimum temperature was found to be between 38° and 39° C. It is also 

 necessary for the cultures to be well aerated and shaken each day. Finally, the 

 strain of cholera spirillum employed must not have been passed through animals, 

 since such a passage diminished the toxic power of the organism with great 

 rapidity. 



Following this method they were able to obtain a cholera toxin with 26 cul- 

 tures of vibrios isolated in Saigon, with two strains obtained from the Pasteur 

 Institute, one of which was isolated in Bombay and the other in Nasik, and 

 with three strains from Egypt. They concluded that a soluble toxin may be 

 obtained from vibrios isolated from cholera stools and that the production of the 

 toxin may be increased by cultivating the organisms in their special culture 



33 Lancet (1906), 171, 495. 



3i Compt. rend. Acad. d. Sc, Par. (1905), 141, 397. 



