140 



EXPERBIEXT STATION 



[Jan. 



little or no diftorence in the ettects of the stimulation on the 

 radicle and hypocotyl. 



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

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

 showing itself shortly after stimulating. 



Fig. 3. — Showing the effects of positive and negative electrical charges on the growth of lettuce 

 seedhngs. 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, 



