380 BACTERIOLOGY. 



surface aud gradually assumes the appearance of a 

 cloudy linear mass with prolongations radiating into 

 the gelatin from all sides. Liquefaction with coinci- 

 dent gas-production results, and may reach almost to 

 the surface of the gelatin. 



Relations to temperature. It grows best under a 

 temperature of from 36° to 38° C. ; gelatin cultures 

 kept at from 20° to 25° C. begin to grow after three or 

 four days. In an atmosphere of hydrogen at from 18° 

 to 20° C, growth does not usually occur before one 

 week. No growth occurs under 14° C. At the tem- 

 perature of the body, spores are formed in cultures in 

 about thirty hours, whereas in gelatin cultures at from 

 20° to 25° C. they do not usually appear before a week, 

 when the lower part of the gelatin is quite fluid. 



Spores of the tetanus bacillus when dried upon bits 

 of thread over sulphuric acid in the desiccator and 

 subsequently kept exposed to the air, retain their vitality 

 and virulence for a number of months. Their vitality 

 is not destroyed by an exposure of one hour to 80° C ; 

 on the other hand, an exposure of five minutes to 

 100° C. in the steam sterilizer kills them. They resist 

 the action of 5 per cent, carbolic acid for ten hours, but 

 succumb when exposed to it for fifteen hours. In the same 

 solution, plus 0.5 per cent, hydrochloric acid, they are 

 no longer active after two hours. They are killed 

 when acted upon for three hours by corrosive subli- 

 mate, 1 : 1000, and in thirty minutes by the same solu- 

 tion plus 0.5 per cent, hydrochloric acid. 



Aoiion upon animah. After subcutaneous inoculation 

 of mice with minute portions of a pure culture of this 

 organism tetanus develops iu twenty-four hours and 

 ends fatally in from two to three days. Rats, guinea- 



