﻿REPORT ON CHOLERA IN MANILA. 435 



media. In the following year 3:i the same authors called attention to the fact 

 that this cholera toxin manifested its effect quickly and without a period of 

 incubation when injected into an animal. Guinea pigs and rabbits could be 

 immunized against the toxin so that they were able to resist two fatal doses 

 injected at one time, and horses which had been inoculated intravenously at 

 intervals of 6 months with \ liter of the toxin, furnished a serum of which 0.02 

 cubic centimeter neutralized two fatal doses of the cholera toxin after a contact 

 of thirty minutes in vitro. The serum also exerted antimicrobic, agglutinating 

 and precipitating qualities. The cholera toxin was not destroyed by boiling and 

 the boiled toxin produced as good a serum as the unboiled one. It was also 

 found that the injection of cultures of the living cholera vibrio into the veins of 

 a horse furnished an antitoxic serum which was even more active than that 

 prepared with the soluble toxin. They admit that the cholera toxin appears to 

 be analogous to the endotoxins of the pest and typhoid bacilli, although in their 

 final conclusions they state that the organism produces a soluble toxin the action 

 of which is rapid and without a period of incubation. They also believe that 

 the cholera toxin contained in the exudates of the bacteria and that obtained 

 in the liquid culture media, can not be distinguished. The authors in their last 

 article emphasize some further precautions to be observed in order to secure a 

 good production of the toxin. The media finally employed consisted of 20 cubic 

 centimeters of normal serum of the horse plus 10 cubic centimeters of defibrinated 

 blood. The serum and defibrinated blood must be at least three weeks old before 

 use, as otherwise almost no production of toxin occurs. 



In 1903-4, in studying the question of protective inoculation against cholera, 

 I called attention to the fact that judging from my experiments "it would appear 

 that the most advantageous method for the extraction of the intracellular toxins 

 of the cholera spirillum would be the one which MacFadyan has recently applied 

 to the typhoid bacillus with the same end in view. By this method the bacteria 

 were ground up at the temperature of liquid air, the disintegration having 

 occurred under conditions which precluded the possibility of chemical change." 



MacFadyan 36 during the present year, 1906, has undertaken experiments of 

 this nature with sterile juices obtained from the cholera organism. Toxic 

 extracts were obtained from the most virulent cultures which killed guinea pigs 

 acutely in doses of 0.1 to 0.05 cubic centimeter while 0.02 cubic centimeter ren- 

 dered the animals ill. The endotoxin also exerted its action when injected 

 subcutaneously in quantities of 1 and 2 cubic centimeters. Doses of 0.1 to 0.05 

 cubic centimeter killed rabbits on intravenous injection. The juices deteriorated 

 in toxic power on keeping, and the latter was destroyed by heating at a tem- 

 perature from 55° to 60° C. Goats were immunized with increasing doses of 

 the endotoxin and a serum was obtained of which 0.002 cubic centimeter neutral- 

 ized from three to four ascertained lethal doses of the endotoxin for a guinea pig. 

 This property was not possessed by 1 cubic centimeter of normal serum. 



Kraus, 37 in 1904, in working with a vibrio designated as "Nasik," was able to 

 obtain a powerful toxin from filtered bouillon cultures of this organism. By 

 heating to 50° C. its poisonous properties were destroyed. Kraus concluded that 

 his organism was not a true cholera vibrio owing to its agglutinative, bactericidal, 

 precipitating, and haemolytic properties. Since this time the same author =s 



3 "Compt. rend. Acad. d. 8c. Par. (1906), 142, 728, and Ann. d. Vinst. Pasteur 

 (1906), 20, 578. 



36 Lancet (1906), 2, 494. 



37 Central, f. Bakteriol. Orig. (1904), 34, 488. 



**Ibid, (1906), 41, 15, and Wien. klin. Wchnsch. (1906), 19', 655. 



