230 PATHOGENIC BACTERIA, 



The toxin is not an albuminous substance, and can be 

 elaborated by the bacilli when grown in non-albuminous 

 urine, or, as suggested by Uschinsky, in non-albuminous 

 solutions whose principal ingredient is asparagin. The 

 toxic value of the cultures is greatest in the second or 

 third week. 



In addition to the toxin, a toxalbumin has been isolated 

 by Brieger and Frankel. 



Behring 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 

 by Roux and others at the present time was first sug- 

 gested by Fernbach, and consists in growing the most 

 virulent bacilli obtainable in alkaline bouillon exposed 

 in a thin layer to the passage of a current of air. 



The cultures are allowed to grow for three or four 

 weeks at a temperature of 37 C., with a stream of 

 moist air constantly passing over them. 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 u ripe," 0.4 per cent, of trikresol 



