MECHANISM OF PROCESS OF DEATH 71 



One striking result of the investigations on toxicity 

 carried out by the writer is to emphasize the fact that the 

 apparent toxicity of two substances may depend very 

 largely upon the stage of the reaction at which the meas- 



140% 



too% 



DEAD 



Fig. 31. — Curves showing changes in the net electrical resistanoe of tissues in two toxic 



solutions, A and B (the latter causes a rise followed by a fall in resistance). Toxicity may be 



measured by determining the time required to carry the reaction to a definite stage, as, for 



example, to 55% which is half way between the normal condition and the death point. 



urement is made. This is evident from an inspection of 

 the curves in Fig. 31. These represent the electrical 

 resistance of Laminaria in sea water and in two toxic 

 solutions. If the tissue be placed in a solution of NaCl 

 of the same conductivity as sea water, the resistance falls, 

 somewhat as shown in Curve A, until it reaches the death 



