288 The Influence of Environment 



to 90 ; while for the spores of the same bacillus a 

 temperature of from 105 to 120 was required. 1 



Duclaux has called attention to a fact which is of 

 importance for the investigation of the upper tempera- 

 ture limit for the life of organisms.. According to this 

 author it is erroneous to speak of a definite temperature 

 as a fatal one; instead we must speak of a deadly- 

 temperature zone. This is due to the fact that the 

 length of time which an organism is exposed to a higher 

 temperature is of importance. Duclaux quotes as an 

 example a series of experiments by Christen on the 

 spores of soil and hay bacilli. The spores were exposed 

 to a stream of steam and the time determined which 

 was required at the various temperatures to kill the 

 spores. 



It took at ioo L over sixteen hours 



" " " 105-1 10° two to four hours 



" " " 1 15 thirty to sixty minutes 



" " " 125-130 five minutes or more 



" " " 135° one to five minutes 



" " " 140 one minute 



In warm-blooded animals 45 is generally considered 

 a temperature at which death occurs in a few minutes; 

 but a temperature of 44°, 43°, or 42 is also to be 

 considered fatal with this difference only, that it takes 



1 Duclaux, E., TraitS de microbiol., 1898, i., 280. 



