TOXINES. 7 



The kind of culture medium naturally has the greatest influence 

 on the production of the poison. 



In general, bouillon cultivations are employed, usually with 

 the addition of a certain proportion of peptone ; but culture 

 media are also frequently prepared from meat extracts, yeast 

 extracts, &c. 



Agar and other nutrient media can hardly be advantageously 

 employed. Interesting experiments have been made to produce 

 toxines in proteid-free culture media, as, for instance, in aspara- 

 gine solutions containing suitable salts (ARMAND and CHARRIN 1 ), 

 and in dialysed urine. Satisfactory results, however, have not 

 yet been obtained (GuiNOCHET, 2 UscHiNSKY 3 ). ZINNO'S* explana- 

 tion of apparently successful attempts to produce toxines in such 

 proteid-free culture media is, that only traces of proteid are 

 necessary for the production of detectable amounts of poison. 

 As a matter of fact, the quantities of toxine thus produced are 

 extremely small. He concludes, from his own experiments, that 

 the presence of a small amount of proteid is indispensable. 



Speaking generally, this factor varies so greatly with the kind 

 of toxine that the reader must be referred to the special part, 

 where a full description is given of the different methods that 

 have been employed to obtain the largest possible yield of 

 toxines. 



Here we will only point out briefly that too great acidity or 

 alkalinity of the medium must always be avoided, and that, in 

 general, the same precautions with regard to temperature, &c., 

 must be observed as are usually taken to obtain the most active 

 and virulent cultivations of bacteria. 



One point, however, of special interest may be mentioned here. 

 The production of a very active and virulent growth of the 

 bacteria themselves is not invariably accompanied by the de- 

 velopment of very energetic cultures of their toxines. For, on 

 the one hand, it would seem that the production of poison by the 

 bacteria is not a direct function of their activity of growth or 

 their high degree of virulence. Indeed, in the case of diphtheria, 



1 Arraand and Charrin, "Transformation de la Matiere organique azote, 

 &c.," Bull. Med., 1891, 356; 1892, 957. Absts. in Centralbl. f. JBakt., xi., 

 248, 1892. Cf. Buchner, " Bakteriengifte und Gegengifte," Munch, med. 



Woch., 1893, 449. 



2 Guinochet, " Contrib. a 1'etude de la toxine du bacille de la diph- 

 therie," ibid., 1893, 293. 



3 Uschinsky, " Les Poisons de la diphthe"rie et du cholera," ibid., 1893, 

 293 



4 Zinno, "Beitr. z. Stud. d. Entstehung der Toxine," Centralbl. f. JBakt., 

 xxxi., 42, 1902. 



