DIPHTHERIA TOXINE. 75 



Too much air and pure oxygen have a very injurious effect 

 upon the poison, especially at the incubation temperature (Roux 

 and YERSIN, MARTIN, MADSEN). 



When cultivations are made in this way with every possible 

 precaution to promote energetic toxic activity, very active toxines 

 are usually obtained in a short time. Even after thirty to forty- 

 eight hours they are unmistakably present. In seven to about 

 thirty days the toxicity reaches its maximum, and then begins 

 very slowly to decline, this being due to a simultaneous decrease 

 of production in the cultivation as it grows old and to the com- 

 mencement of the formation of toxoids. The transplantation of 

 cultivations again restores their toxigenic power (Roux and 

 YERSIN). As a general rule, then, in testing primary poisons, 

 cultivations are used that are not more than three weeks' old 

 (MADSEN, loc. cit.). For immunising purposes, however, much 

 older poisons can frequently be used with advantage, since the 

 toxoids they contain have also an immunising action. 



The development of a bouillon of the greatest possible toxicity 

 does not invariably correspond with that of a particularly viru- 

 lent living cultivation ; sometimes bacilli that are only slightly 

 virulent may produce extremely active toxines (MARTIN, loc. cit.). 



On the other hand, there are also varieties of diphtheria bacilli 

 that possess neither virulence nor toxigenic power. LUBOWSKI J 

 has described an instance of this kind. A bacillus of human 

 origin produced no active toxines whatsoever, whereas the serum 

 of the child was strongly antitoxic. The inference is that the 

 bacillus had been very toxigenic, but that it had completely lost 

 its powers. 



In general, the production of poison shows extraordinary 

 variations, and its amount cannot be estimated beforehand, even 

 in the case of a similar cultivation in the same nutrient medium. 

 MADSEN has vainly endeavoured to explain these variations the 

 kind of flasks and the sterilisation of the nutrient medium have 

 no influence on the results. 



We have reached such a stage in the preparation of the poison 

 of diphtheria bacilli that for immunising purposes we now use 

 only poisons 0-02 c.c. of which will kill with acute symptoms 

 guinea-pigs of 250 grms. The essential conditions for the pro- 

 duction of the virus are : 



1. A suitable cultivation which grows upon the surface i.e., 

 develops on the bouillon in the form of a membrane ; 



2. Alkalinity of the bouillon ; 



1 Lubowski, " Ueb. einen atoxischen- und avirulenten Diphtheriestamm," 

 Zeit.f. Hyg., xxxv., 87, 1900. 



