170 TECHNOLOGY OF BACTERIA. 



of time and material which results from imperfect 

 sterilization is annoying, and mistakes may arise 

 from a false confidence in the success of the opera- 

 tion. To avoid these, it is always best to test 

 culture-fluids in the culture-oven for several 

 days before using them for any experiment. 



The maintenance of a boiling temperature at 

 intervals for a day or two is more effectual than 

 the same amount of continuous boiling. Pasteur 

 has shown that an alkaline fluid is more difficult to 

 sterilize than one having an acid reaction. The 

 vitality of bacteria in active growth is destroyed 

 by a comparatively low temperature. Thus Chau- 

 veau has recently made the statement (C. E. Ac. 

 des Sc., t. XCIV. p. 1694), that the anthrax bacil- 

 lus is killed (in blood) by exposure for nine or ten 

 minutes to a temperature of 54 (129.2 Fahr.). 

 According to Fnsch, B. termo is killed by a tem- 

 perature of 45 to 50 (113 to 122 Fahr.) time 

 of exposure not given. The writer has fixed the 

 thermal death-point of the micrococcus of induced 

 septicaemia in the rabbit at 60 (140 Fahr.), the 

 time of exposure being ten minutes; that of Mi- 

 crococcus ureae was found to be the same. 



The method adopted by Koch for the ^teriliza- 

 tion of blood-serum for his experiments with the tu- 

 bercle bacillus has already been mentioned (p. 163). 

 This method depends for success upon the fact that 

 the temperature employed, 58, is sufficient to de- 

 stroy growing bacteria, and that in the intervals 

 between the daily heating for one hour the spores 



