CHAPTER XL — MODE OF LIFE OF THE BACTERIA. 477 



the Bacillus in question also possess wonderful powers of withstanding extremely 

 high temperatures. Even in a fluid they are proof against a temperature higher 

 than that of boiling water. Brefeld 1 found that they all germinated after being 

 boiled for a quarter of an hour in a nutrient solution, the greater part of them after 

 half an hour of the same treatment, a smaller number after the space of one hour, none 

 when the boiling had continued for three hours. When spores were heated in 

 nutrient solutions up to 105 C. they were killed in 15 minutes, up to io7°C. in 10, 

 and up to no C. in 5 minutes. 



Fitz found in 1882 that the spores of his Bacillus butylicus (? B. butyricus of 

 Prazmowski) endured a temperature of ioo° C. for a period varying from 3 to 20 

 minutes, according to the special quality of the spores and the medium employed. 

 Temperatures below ioo° C. were sufficient to kill the spores when they were exposed 

 to them for a longer continuance. In solution of glycerine death ensued in 2-6 

 hours at a temperature of 95° C, in 6-1 1 hours at 90 C, in 7-1 1 hours at 8o° C. ; 

 vitality was not destroyed after exposure for 12 hours to a temperature of 70 C. The 

 power of resistance was less in a solution of grape-sugar ; the spores were killed in 

 6 hours at a temperature of 90 ° C. 



Buchner 2 found that some of the spores of the Bacillus of anthrax were killed 

 by being boiled in water for two and three hours, and that after four hours' time they 

 were all dead. Those of Bacillus Megaterium retain their power of germination after 

 being boiled in water for a few minutes. Of spores of less certain derivation occurring 

 in ordinary waters Pasteur states that they can even withstand a temperature of 130 . 



These facts, and statements of a similar kind occurring in publications on 

 Bacteria, make it probable that the death-point for the spores of the Endosporous 

 Bacteria is generally very high, though it varies with the nature of the medium. 

 But here as elsewhere results obtained in one case must not be at once assumed 

 to be certainly true in others, since Brefeld in the work from which we have 

 quoted has shown that the spores of a form of Bacillus, not B. subtilis, will not live 

 in boiling water. 



That the spores of Bacteria are able to bear extremely low temperatures has not 

 been proved by direct experiment, but may be concluded from the behaviour of the 

 vegetating cells which will be considered below. 



The account given in section XCVI of the external conditions of germin- 

 ation is also generally true of the Bacteria, and to this the reader is referred. 



The minimum and optimum temperature required for germination 

 especially in the Endosporous Bacteria appear to be usually high, other conditions 

 being equally favourable ; at least most of the experiments show that germination does 

 not take place or is very slow in the temperature of an ordinary room, and becomes 

 active only when the temperature is raised. In the case of Bacillus subtilis the 

 minimum is certainly below the temperature of an ordinary room, for germination 

 proceeds in it, though slowly. According to Prazmowski from 3o°-35° C. is 

 near the optimum ; I myself have seen spores some days old germinate in the most 

 vigorous manner in a temperature of 40° C. three hours after they were sown. Bacillus 



1 Schimmelpilze, IV. 



2 See Nageli, tlnters. ii. niedere Pilze (1882), p. no. 



