BACILLUS DIPHTHERIA 521 



toxin-producing power of B. diphtheria?. Experiments by Hilbert, x 

 Theobald Smith, 2 and others seem to have given support to this view. 



The medium most frequently employed for the production of toxin 

 is a beef-infusion broth. There are minor differences of opinion as to 

 the most favorable constitution of this medium for the production of 

 toxin. All agree, however, in recognizing the importance of peptone, 

 without which, according to Madsen, 3 no satisfactory toxin has yet been 

 produced. This is added in proportions of from one to two per cent. 

 The presence of sugars in the medium is not desirable in that it leads 

 to acid production; L. Martin 4 removes the sugars from the meat by 

 fermentation with yeast. Smith 5 accomplishes the same purpose with 

 B. coli. According to Park and Williams. 6 however, this is super- 

 fluous, 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. 

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

 acid and, while this continues, there is, as Spronk 7 has shown, little 

 or no evidence of toxin elaboration. Park and Williams, 8 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 

 litmus, Y 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 OP DIPHTHERIA 

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

 Brieger and Frankel, 9 by repeated precipitation with alcohol, suc- 



1 Hilbert, Zeit. f . Hyg., xxix, 1898. 2 Smith, Medical Rec., May, 1896. 



3 Madsen, Kraus und Levaditi, "Handbuch d. Technic," etc., 1907. 



4 L. Martin, Ann. de 1'inst. Pasteur, 1897. 

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



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



7 Spronk, Ann. de 1'inst. Pasteur, 1895. 



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



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



