BACILLUS DIPHTHERIA 573 



litmus, N/l 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 obtained 

 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, 28 by repeated precipitation with alcohol, suc- 

 ceeded 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 useful protein reactions, but dif- 

 fered from proteins 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 representing intermediate phases in the peptoniza- 

 tion of albumins. Similar results have been obtained by Wassermann 

 and Proskauer, 29 Brieger and Boer, 30 and others. Uschinsky, 31 on 

 the other hand, has disputed the protein nature of toxins in general, 

 having produced diphtheria toxin by growing the organism upon a 

 medium entirely free from albuminous bodies. Uschinsky believes 

 that the protein reactions observed by others may be due to ingredients 

 of the precipitates other than the toxin. It is not impossible, however, 

 that the organisms may have produced protein substances by synthesis 

 from the simpler substances in Uschinsky's medium. The production 

 of toxin from such a medium, therefore, is not a conclusive argument 

 against the protein nature of toxins. Accurate chemical isolation and 

 analysis of diphtheria toxin have not yet been accomplished. 



Diphtheria toxin is destroyed, 32 when in the fluid form, by tempera- 

 tures of 58 to 60 C. In the dry state, it resists a temperature of 70 C. 

 and over, without change. Light and free access of air produce rapid 

 deterioration. Sealed, protected from light, and kept at almost freezing 



28 Brieger imd Frankel, Berl. klin. Woch., xi_xii, 1889. 



-'' \\' asxcrmann nnd /Vo.s7,Y////', Dent. med. Woch., 1891, p. 585. 



3(1 Itricyer nnd Boer, Dcut. mod. Woch., 1896, p. 783. 



31 UschinsTcy, Cent, f . Bakt., xxi, 1897. 



82 Roux et Yersin, loc. cit. 



