BACILLUS DIPHTHERIA 521 



talion with yeast. Smith l accomplishes the same purpose with B. coli. 

 According to Park and Williams, 2 however, this is superfluous, the 

 ' quantity of sugar present in ordinary butcher's meat not being sufficient 

 to exert unfavorable influence. 



Experience has shown that a primary alkaline reaction offers the 

 most favorable conditions for toxin production. In all cultures of B. 

 diphtherias in non-sugar free broth, there is, at first, a production of 

 acid and, while this continues, there is, as Spronk 3 has shown, little 

 or no evidence of toxin elaboration. Park and Williams, 4 in an inquiry 

 into the question of reaction, came to the conclusion that the best 

 results are obtained with a broth to which, after neutralization to lit- 

 mus, f NaOH is added in an amount of 7 c.c. to the liter. In such a 

 medium the largest yield of toxin is obtained after about five to eight 

 days' growth at a temperature of 37.5 C. 



Free access of oxygen to the culture medium during the growth 

 of the organisms has been found to be of great importance. Roux ob- 

 tained this by passing a stream of oxygen through the bouillon. The 

 supply is quite sufficient for practical purposes, however, if the medium 

 is distributed in thin layers in large-necked Erlenmeyer flasks. 



CHEMICAL NATURE AND PHYSICAL PROPERTIES OF DIPHTHERIA 

 TOXIN. The chemical composition of diphtheria toxin is not known. 

 Brieger and Frankel, 5 by repeated precipitation with alcohol, succeeded 

 in extracting from toxic bouillon a white, water-soluble powder which 

 possessed most of the poisonous properties of the broth itself. This, in 

 solution, gave many of the usuaj proteid reactions, but differed from pro- 

 teids in failing to coagulate when boiled and in not giving precipitates 

 when treated with magnesium sulphate, sodium sulphate, or nitric acid. 

 It was believed by them to be closely related to the albumoses, bodies rep- 

 resenting intermediate phases in the peptonization of albumins. Similar 

 results have been obtained by Wassermann and Proskauer, 6 Brieger and 

 Boer, 7 and others. Uschinsky, 8 on the other hand, has disputed the 



1 Th. Smith, Jour. Exp. Med., iv, 1899. 



2 Park and Williams, Jour. Exp. Med., 1897. 



3 Spronk, Ann. de 1'Inst. Pasteur, 1895. 



4 Park and Williams, Jour. Exp. Med., 1897. 



5 Brieger und Frankel, Berl. klin. Woch., xi-xii, 1889. 



6 Wassermann und Proskauer, Deut. med. Woch., 1891, p. 585. 



7 Briefer and Boer, Deut. 'med. Woch., 1896, p. 783. 

 Uschinsky, Cent. f. Bakt., xxi, 1897. 



