ELECTRIC RESPONSE 15 



say, I desired to know, with regard to plants, what was 

 the relation between intensity of stimulus and the cor- 

 responding response ; what were the effects of super- 

 position of stimuli ; whether fatigue was present, and 

 in what manner it influenced response ; what were 

 the effects of extremes of temperature on the response ; 

 and, lastly, if chemical reagents could exercise any in- 

 fluence in the modification of plant response, as stimu- 

 lating, anesthetic, and poisonous drugs have been found 

 to do with nerve and muscle. 



If it could be proved that the electric response 

 served as a faithful index of the physiological activity 

 of plants, it' would then be possible successfully to 

 attack many problems in plant physiology, the solution 

 of which at present offers many experimental difficul- 

 ties. 



With animal tissues, experiments have to be carried 

 on under many great and unavoidable difficulties. The 

 isolated tissue, for example, is subject to unknown 

 changes inseparable from the rapid approach of death. 

 Plants, however, offer a great advantage in this respect, 

 for they maintain their vitality unimpaired during a 

 very great length of time. 



In animal tissues, again, the vital conditions them- 

 selves are highly complex. Those essential factors 

 which modify response can, therefore, be better deter- 

 mined under the simpler conditions which obtain in 

 vegetable life. 



In the succeeding chapters it will be shown that the 

 response phenomena are exhibited not only by plants 

 but by inorganic substances as well, and that the 



