CHAPTER XI.—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! 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 107°C. in 10, 
and up to r10°C. in 5 minutes. 
Fitz found in 1882 that the spores of his Bacillus butylicus (? B. butyricus of 
Prazmowski) endured a temperature of 100°C. for a period varying from 3 to 20 
minutes, according to the special quality of the spores and the medium employed. 
Temperatures below 100° 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 6-11 hours at 90° C., in 7-11 hours at 80°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? 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 30°-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. 
? See Nageli, Unters. ii. niedere Pilze (1882), p. 220. 
