462 PATHOGENIC MICROORGANISMS 



salt solution, and therefore permits of the preparation of uniform solu- 

 tions for purposes of standardization. 



Brieger and Boer l have also succeeded in precipitating the toxin 

 out of broth solution with zinc chloride. Vaillard and Vincent 2 have 

 procured it in the dry state by evaporation in vacuo. 



Brieger and Cohn, 3 Brieger and Boer, 4 and others have attempted 

 to isolate tetanus poison, removing the proteids from the ammonium sul- 

 phate 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 proteid reactions. 



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

 sato 5 states that exposure to 68 C. for five minutes destroys it com- 

 pletely. Dry toxin is more resistant, 6 often withstanding temperatures 

 of 120 C. for more than fifteen minutes. Exposure to direct sunlight 

 destroys the poison in fifteen to eighteen hours. 7 



Interesting experiments as to the action of eosin upon tetanus toxin 

 have been carried out by various observers. Flexner and Noguchi 8 

 found that five per cent eosin added to the toxin would destroy it 

 within one hour. This action is ascribed to the photodynamic power 

 of the eosin. 



The toxin exerts an extremely low osmotic pressure and is easily 

 destroyed by electric currents. 



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 ammo- 

 nium sulphate precipitation 9 is quantitatively even stronger, values of 

 0.000,001 grams as a lethal dose for a mouse of the given weight not 

 being uncommon. Brieger and Cohn 10 succeeded in producing a dry 

 toxin capable of killing mice in doses of 0.000,000,05 gram. 



Different species of animals show great variation in their suscepti- 



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



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



3 Brieger und Cohn, loc. cit. 



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



5 Kitasato, Zeit. f . Hyg., x. 



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



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



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



9 Brieger und Cohn., loc. cit. 



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



