FORMATION! AND GERMINATION OF SPORES. 109 



The resistance is tested by simply hanging in the 

 steam chamber little tulle bags containing fragments 

 or bits of glass upon which anthrax spores have been 

 dried. From minute to minute a bag is removed and 

 the bits of glass placed upon an agar plate which is 

 kept at incubating temperature. Anthrax spores are 

 obtained by careful removal of sporulating agar streak 

 cultures, and warming the emulsion, prepared with 

 little water, to 70 for five minutes. 



The varying resistance of apparently identical an- 

 thrax spores possesses great practical importance: 

 (1) in disinfection tests which may be made only 

 with spores of known resistance ; (2) in differential 

 diagnosis, because it shows that we must be on our 

 guard against creating two species based on a differ- 

 ence in resistance. 



Various forms which occur in hay and soil possess 

 remarkable resistance. 



Christen found (C. B., XYII., p. 498), for example, 

 that in steam under pressure the resisting spores of 

 the soil required for their destruction : At 100, more 

 than sixteen hours; 105-110, two to four hours; 

 115, thirty to sixty minutes; 125-130, five minutes 

 or more; 135, one to five minutes ; 140, one minute. 

 The apparatus raised objects very rapidly to the de- 

 sired temperature. 



Spores are also very resistant to chemical agents. 

 Thus, anthrax spores require, according to their origin 

 (v. Esmarch : 1. c. ) a five-per-cent solution of carbolic 

 acid at least two days, in some cases even forty days. 

 A one-per-cent aqueous solution of corrosive subli- 

 mate is withstood by very resistant anthrax spores as 

 much as three days, although their virulence was lost 



