INFLUENCE OF TEMPERATURE UPON LIFE-PROCESSES 425 



It is obvious that here we are dealing with a phenomenon of quite 

 a distinct nature from the other phenomena of life which we have 

 hitherto being considering, and the question immediately suggests 

 itself whether any clue exists as to the origin of this remarkable 

 susceptibility to temperature. Now on comparing the temperature- 

 coefficients of various reactions involving Enzymes, one group stands 

 out from all the rest by reason of the extraordinary magnitude of the 

 temperature-coefficients, and that is the group afforded by the Auto- 

 destruction which various enzymes undergo in solution. The following 

 data are cited after Arrhenius : 



Numerical value 

 Nature of process. of /*. 



Hydrolysis of sugar by acids 25,600 



invertase 9,080 



Saponification of ethyl acetate by NaOH 11,150 



triacetin by lipase 16, 700 



cottonseed oil by lipase 



Digestion of gelatin by pepsin 



trypsin .... 



" egg-white by pepsin .... 



Coagulation of milk by rennet .... 



Spontaneous destruction of trypsin in solution 



" " pepsin in solution 



7,540 

 10,750 

 10,570 

 15,570 

 20,650 

 62,034 

 75,600 



rennet in solution . ...... 90,000 



vibriolysin in solution ...... 128,000 



tetanolysin in solution ...... 162,000 



hemolysin in solution . . . . % . .198,500 



The relationship between the value of M in the equation: 



and the temperature-coefficient for the ten-degree interval between 

 20 and 30 C. is shown in the following table: 



A temperature- Corresponding to the 



coefficient of value of 



2 ................ 13,200 



10 ................ 44,000 



100 ................ 88,000 



1,000 ......... ....... 132,000 



10,000 ......... ....... 176,000 



It is evident therefore that the temperature-coefficient of the 

 duration of life corresponds not at all with that of enzymatic hydrol- 

 yses, but it is, on the other hand, of precisely the order of magnitude 

 encountered in the autodestruction of enzymes or of specific anti- 

 bodies. It is to the destruction of enzymes, consequently, that we 

 may attribute the thermal death of organisms excepting in those cases, 

 as in spores of seeds, in which the essential tissue-enzymes are thermo- 

 stabile and the temperatures required to kill the tissue are those which 



