﻿436 STRONG. 



has carried on extensive experiments with a number of different vibrios, which 

 can not here be considered in detail. In his most recent article on the subject 30 

 he concludes that the cholera vibrio of Koch produces no haemotoxin either in 

 buillon cultures or in goat's blood-agar plates. However, it gives rise to a toxin 

 which is either produced by the spirillum only in the living organism, or also 

 in vitro. The cholera poison is a true, soluble toxin and may be destroyed by 

 antitoxin. It is to be differentiated from Pfeiffer's endogenous poison, which 

 in the organism produces no antitoxin. Cholera is therefore an intoxication which 

 is excited by a secreted, soluble toxin. 



A study of Kraus' experiments does not seem to me entirely to justify 

 his conclusions. Moreover, his results are not altogether in accord with 

 those of Brau and Denier. Kraus distinguishes two kinds of soluble 

 poisons in the different spirilla, one, which is the most potent, acutely act- 

 ing toxin, such as that produced by the Vibrio nasik, and a large number 

 of other not true cholera vibrios, and a second which is a slowly acting, 

 poisonous substance encountered in filtrates of true cholera cultures and 

 which he regards as the toxin which gives rise to the cholera symptoms 

 observed in man. Brau and Denier state that the toxin they obtained 

 from the cholera vibrio acts acutely and without an incubation period, 

 and that the)' secured this toxin from the Vibrio nasik, as well as from 

 many other undoubted cholera strains. The toxin with which they 

 worked was not destroyed by boiling, while the one which Ivraus obtained 

 from the Vibrio nasik was destroyed at a temperature of 50° C. How- 

 ever, Brau and Denier in their last publication on this subject incline to 

 the belief that they formerly encountered two toxins, one of which was 

 destroyed by boiling and the other not. Kraus has apparently lost sight 

 of the fact that MaeFadyan has obtained an anti-endotoxic serum of such 

 potency that 0.002 cubic centimeter protected a guinea pig against three 

 lethal doses of the cholera endotoxin, while Brau and Denier found that 

 0.002 cubic centimeter of horse's cholera immune serum, the animal hav- 

 ing received 0.5 liter of toxin intravenously, was able to neutralize but 

 two fatal doses of the toxin after standing one-half hour in vitro. This 

 serum did not follow the law of multiples, as 0.05 of a cubic centimeter 

 was necessary to neutralize 3 lethal doses of toxin, while 1 cubic centi- 

 meter was required to neutralize 4 doses. 



I demonstrated in 1903 that 0.2 cubic centimeter of a cholera anti- 

 endotoxic serum would neutralize 4 lethal doses of toxin, when mixed 

 immediately before inoculation. I also found, as MaeFadyan has since 

 done, that a temperature of 60° C. destroys most of this primary poison, 

 or at least converts the toxin into toxoid. It would appear that the toxin 

 which Kraus has obtained and which he designates as a secretion of the 

 organism and as a soluble toxin, is none other than the one with which 

 Brau and Denier, MaeFadyan. and myself worked and that it should 



sa OentrU. f. Bakteriol. Referate, (1906), 38, Beil. 84. 



