288 The Influence of Environment 



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

 temperature of from 105° to 120° was required.' 



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 100^ over sixteen hours 



" 105-1 10° two to four hours 



115° thirty to sixty minutes 



125-130° five minutes or more 



" 135° one to five minutes 



140° one minute 



4( 

 <( 



<( 

 (( 



(( 



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 



» Duclaux, E., Traite de microbioL, 1898, i., 280. 



