io8 



DYNAMICS OF LIVING MATTER 



plasm influences the temperature 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 is not sufficiently long, only 

 part of the colloid coagulates; in this case an organism may again 

 recover. We gain from these experiments a further confirmation of the 

 idea expressed in an earlier lecture, that the process of coagulation or 

 gelation may not be a purely physical process, but the outcome of a 

 chemical reaction. 



When we analyze the effects of heat upon life below the upper fatal 

 temperature zone, we must first realize that the velocity of chemical 

 reactions is raised to two or more times its original amount, whenever 

 the temperature advances 10 C. (van't Hoff and Arrhenius). This 

 holds good for the reactions in living organisms as well as for non- 

 living, as may be seen from the following table concerning the influence 

 of temperature upon the CO 2 production by seeds of lupines: 100 gr. 

 of seeds produced in one hour according to Clausen,* the following 

 number of milligrams of CO 2 : 



TEMPERATURE 



10 



15 



20 



2 5 

 3 



35 

 40 



45 

 5 



55 



CO 2 PRODUCED 



7.27 

 13.86 



iS.ir 



34-37 

 43-55 

 58.76 

 85.00 



IOO.OO 



115.90 



104.45 



46.20 



17.70 



We see that below the temperature of 40 the amount of CO 2 is approxi- 

 mately doubled for every rise of 10 in temperature. Above this 

 temperature, however, the amount of CO 2 diminishes rapidly with any 

 further increase of the temperature. This is very generally observed 

 in enzymatic processes, and may be due to the fact that the enzyme 

 itself undergoes hydrolysis, which of course follows the temperature 

 law of van't Hoff and Arrhenius ; t or it may be that the enzyme 

 undergoes heat coagulation (or a process of clumping), by which 



* Quoted after Cohen, Lectures on Physical Chemistry for Physicians and Biologists, 

 New York, 1902. 



t Tammane, Zeitsch. fur physikal Chemie, Vol. 18, p. 426, 1895. 



