732 PATHOGENIC MICROORGANISMS 



permits of the preparation of uniform solutions for purposes of 

 standardization. 



Brieger and Boer 14 have also succeeded in precipitating the toxin 

 out of broth solution with zinc chloride. Vaillard and Vincent 15 

 have procured it in the dry state by evaporation in vacuo. 



Brieger and Cohn, 16 Brieger and Boer, 17 and others have at- 

 tempted to isolate tetanus poison, removing the proteins from the 

 ammonium sulphate precipitate by various chemical methods. The 

 purest preparations obtained have been in the form of fine yellowish 

 flakes, soluble in water, insoluble in alcohol and ether. Solutions 

 of this substance have failed to give the usual protein reactions. 



The toxin when in solution is extremely sensitive to heat. Kita- 

 sato 18 states that exposure to 68 C. for five minutes destroys it 

 completely. Dry toxin is more resistant, 19 often withstanding tem- 

 peratures of 120 C. for more than fifteen minutes. Exposure to 

 direct sunlight destroys the poison in fifteen to eighteen hours. 20 



Interesting experiments as to the action of eosin upon tetanus 

 toxin have been carried out by various observers. Flexner and 

 Noguchi 21 found that five per cent eosin added to the toxin would 

 destroy it within one hour. This action is ascribed to the photo- 

 dynamic power of the eosin. 



Tetanus toxin is one of the most powerful poisons known to us. 

 Filtrates of broth cultures, in quantities of 0.000,005 c.c., will often 

 prove fatal to mice of ten grams weight. Dry toxin obtained by 

 ammonium sulphate precipitation 22 is quantitatively even stronger, 

 values of 0.000,001 gram as a lethal dose for a mouse of the given 

 weight not being uncommon. Brieger and Cohn 23 succeeded in pro- 

 ducing a dry toxin capable of killing mice in doses of 0.000,000,05 

 gram. 



Different species of animals show great variation in their sus- 

 ceptibility to tetanus toxin. Human beings and horses are probably 



14 Brieger und Boer, Zeit. f. Hyg. xxi. 



15 Vaillard et Vincent, Ann. de 1'inst. Pasteur, 1891. 



16 Brieger und Cohn, loc. cit. 



17 Brieger und Boer, Zeit. f. Hyg., xxi. 



18 Kitasato, Zeit. f . Hyg., x. 



19 Morax et Marie, Ann. de 1'inst. Pasteur, 1902. 



20 Fermi und Pernossi, Cent, f . Bakt., xv. 



21 Flexner and Noguchi, "Studies from Rockefeller Inst.," v., 1905. 



22 Brieger und Cohn., loc. cit. 



* Brieger und Cohn, Zeit. f . Hyg., xv. 



