20 CELLULAR 



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, ac- 

 tively growing cell. 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 upsets 

 the normal balance and causes injury so that the 

 life process comes to a standstill. 



The process of death which occurs in a solu- 

 tion of sodium chloride may be checked by add- 

 ing a little calcium chloride to the solution. In 

 this case we speak of antagonism between so- 

 dium 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. 



When the plant is injured and the resistance 

 falls, we may consider that the loss of resistance 

 gives a measure of the amount of injury. This 



