520 BACTERIOLOGY. 



posure of one and one-half hours to 55° C. ; of twenty 

 minutes to 60° C. ; and of five minutes to 65° C. 



"By drying at the temperature of the body under 

 access of air the poison is destroyed ; but by drying at 

 the ordinary temperature of the room, or at this tem- 

 perature in the desiccator over sulphuric acid, it is not 

 destroyed. 



"Diffuse daylight diminishes the intensity of the 

 poison. Its intensity is preserved for a much longer 

 time when kept in the dark. 



" Direct sunlight robs it of its poisonous properties 

 in from fifteen to eighteen hours. 



"Its activity is not diminished by diluting a fixed 

 amount with water or nutrient bouillon. 



" Mineral acids and strong alkalies lessen its intensity." 



The chemical nature of this poison is not positively 

 known, but according to the observations of Brieger 

 and Cohn ^ its designation of " Toxalbumen " is a mis- 

 nomer, for its reactions do not warrant its classification 

 with the albumins in the sense in wiiich the word is 

 commonly used. When obtained in a pure, concentrated 

 form, its toxic properties are seen to be altered by acids, 

 by alkalies, by sulphuretted hydrogen, and by tempera- 

 tures above 70° C. Even when carefully protected from 

 light, moisture, and air, it gradually becomes diminished 

 in strength, doubtless due to the formation of " toxons " 

 and " toxoids," analogous to those observed by Ehrlich in 

 deteriorating diphtheria toxin. When freshly prepared 

 by the methods of the authors just cited, its potency is 

 almost incredible, 0.00005 milligramme being sufficient to 

 cause fatal tetanus in a mouse weighing fifteen grammes. 



' Zeitschrift fur Hygiene und Infektionskrantheiten, 1893, Bd. xv. 

 S. 1. 



