Toxic Products 



455 



tire mass of gelatin and resolve it into a grayish-white 

 syrupy liquid, at the bottom of which the bacilli accu- 

 mulate. The growth in gelatin con- 

 taining glucose is rapid. 



Agar-agar. The growth in agar- 

 agar punctures is slower, but similar 

 to the gelatin cultures except for the 

 absence of liquefaction. 



Vital Resistance. The tetanus 

 spores may remain alive in dry earth 

 for many years. Sternberg says they 

 can resist immersion in 5 per cent, 

 aqueous carbolic acid solutions for ten 

 hours, but fail to grow after fifteen 

 hours. A 5 per cent, carbolic acid 

 solution, to which 0.5 per cent, of 

 hydrochloric acid has been added, 

 destroys them in two hours. They 

 are destroyed in three hours by 

 i : 1000 bichlorid of mercury solu- 

 tion; but when to such a solution 

 0.5 per cent, of hydrochloric acid is 

 added, its activity is so increased 

 that the spores are destroyed in 

 thirty minutes. According to 

 Kitasato,* exposure to streaming 

 steam for from five to eight minutes 

 is certain to kill tetanus spores, and 

 this statement has found its way 

 into most of the text-books without 

 discussion. Theobald Smith, f how- 

 ever, has studied several cultures 

 of the organism, and finds that its 

 resistance to heat is much greater, 

 and that in one case seventy minutes' 

 exposure to steaming steam did not 

 kill all of the spores. 



Toxic Products. Bouillon cul- 

 tures of the tetanus bacillus contain 

 a powerful toxin in solution. 



The most ready method of pre- 

 paring it for experimental study is 



* "Zeitschrift fur Hygiene," vn, p. 225. 



t "Jour. Amer. Med. Assoc.," March 21, 1908, vol. L, No. 12, p. 931. 



Fig. J 39- Tetanus 

 bacillus ; glucose-agai 

 culture, five months old 

 (Curtis). 



