140 



EXPERIMENT STATION. 



[Jan. 



little or no dilTciTnec in the effects of the stimulation on the 

 radicle and hypocotyl. 



The effects of a series of charges from a static machine last 

 only two or three days, the maximum effect of the stimulus 

 showing itself shortly after stimulating. 





Fio. 3. — Showing the effecta of positive and negative electrical charges on tlie growth of lettuce 

 seedlings. Average of three experiments. 



The roots and stems of plants react positively and negatively 

 to various stimuli such as are afforded by gravity, light, mois- 

 ture, chemical substances, etc. It is also well known that the 

 same stimuli will induce reactions of an exactly opposite char- 

 acter in the same organism, or even in the same organ. Usually, 



