The Influence of Environment 289 



a longer time to bring about death. _ This fact is to be 

 considered in the treatment of fever. 



It is generally held that death in these cases is due 

 to an irreversible heat coagulation of proteins. Ac- 

 cording to Duclaux, it can be directly observed in 

 micro-organisms that in the fatal temperature zone 

 the normally homogeneous, or finely granulated, proto- 

 plasm is filled with thick, irregularly arranged bodies, 

 and this is the optical expression of coagulation. The 

 fact that the upper temperature limit differs so widely 

 in different forms is explained by Duclaux through 

 differences in the coagulation temperature of the various 

 proteins. It is, e. g. known that the coagulation 

 temperature varies with the amount of water of the 

 colloid. According to Cramer, the mycelium of Peni- 

 cillium contains 87.6 water to 12.4 dry matter, while 

 the spores have 38.9 water and 61. 1 dry substance. 

 This may explain why the mycelium is killed at a 

 lower temperature than the spores. According to 

 Chevreul, with an increase in the amount of water, 

 the coagulation temperature of albuminoids decreases. 

 The reaction of the protoplasm influences the tempera- 

 ture of coagulation, inasmuch as it is lower when the 

 reaction is acid, higher when the reaction is alkaline. 

 The experiments of Pauli show also a marked influence 

 of salts upon the temperature of coagulation of colloids. 



The process of heat coagulation of colloids is also a 

 function of time. If the exposure to high temperature 

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