408 PATHOGENIC BACTERIA. 



Behring 1 discovered that the blood of animals rendered 

 immune to diphtheria by inoculation, first with attenu- 

 ated and then with virulent organisms, contained a neu- 

 tralizing substance which was capable of annulling the 

 effects of the bacilli or the toxin when simultaneously or 

 subsequently inoculated into non-protected animals. This 

 substance, in solution in the blood-serum of the immu- 

 nized animals, is the diphtheria antitoxin. 



The preparation of the antitoxin for therapeutic pur- 

 poses received a further elaboration in the hands of Roux. 

 The subject is one of great interest, but must be consid- 

 ered briefly in a work of this kind. 



The antitoxin is manufactured commercially at present, 

 the method being the immunization of large animals to 

 great quantities of the toxin, and the withdrawal of their 

 antitoxic blood when the proper degree of immunity has 

 been attained. The details are as follows : 



The Preparation of the Toxin. — The method employed 

 at the present time consists in growing the most virulent 

 bacilli obtainable in alkaline bouillon for from five to 

 seven days at a temperature of 37 C. After the given 

 time has passed, it will be found that the acidity prima- 

 rily produced by the bacillus gives place to a much more 

 intense alkalinity than originally existed. The acme of 

 the toxin-production seems to keep pace with this alka- 

 line production. When ' ' ripe, " o. 4 per cent, of trikresol 

 is added to the cultures, which are then filtered through 

 porcelain or paper, or even simply allowed to sediment. 

 As the dead bacilli are not irritating, their presence is 

 harmless. If the bacillus employed is virulent and the 

 conditions of culture favorable, the filtered culture should 

 be so toxic that 0.0025-0.005 would be fatal to a 250-gram 

 guinea-pig within four days. 



Park and Williams 2 did an elaborate work upon the 

 production of diptheria toxin. They found that "toxin 

 of sufficient strength to kill a 400-gram guinea-pig 



1 Die Blutserumtherapie. 



2 Jour, of Exper. Med., vol. i., No. I, Jan., 1896, p. 164. 



