16 INJURY, RECOVERY, AND DEATH 



ditions. We find that in testing these predictions we 

 must ascertain when the death process reaches a definite 

 stage, (i. e., when it is one-fourth or one-half completed). 

 This can be determined experimentally with a satisfac- 

 tory degree of accuracy. 



We can therefore follow the process of death in the 

 same manner that we follow the progress of a chemical 

 reaction in vitro ; in both cases we obtain curves which 

 may be subjected to mathematical analysis, from which 

 we may draw conclusions regarding the nature of the 

 process. This method has been fruitful in chemistry 

 and it is possible that it may prove equally so in biology. 



Studies undertaken from this point of view lead us 

 to look upon the death process as one which is always 

 going on, even in a normal, actively growing cell. 1 In 

 other words we regard the death process as a normal 

 part of the life process, producing no disturbance unless 

 unduly accelerated by an injurious agent which up- 

 sets the normal balance and causes injury so that the life- 

 process comes to a. standstill. 



The process of death which occurs in a solution of 

 NaCl may be checked by adding a little CaCl 2 to the 

 solution. In this case we speak of antagonism between 

 sodium and calcium. When the calcium is added in the 

 proper proportion the fall of resistance is very slow and 

 the tissue lives for a long time. Any deviation from 

 this optimum proportion hastens death. 



In order to explain these results we may assume that 



1 The general conception that the death process goes on continually 

 is in harmony with the ideas expressed by many physiologists from 

 Claude Bernard (1879; I, 28), down to the present day. Cf. Lipschiitz, 

 A. (1915). 



