502 LIFE MOVEMENTS IN PLANTS 



positivity occurring at the perceptive layer. In vigorous 

 specimens the excitatory negative electric change on the 

 upper side is greater than the positive electric change on 

 the lower side. Depressed condition of the tissue is attend- 

 ed by a relatively greater decline of the negative in 

 comparison with the positive. 



The induced electric variation on the upper and on 

 the lower side indicates that the layers of tissue contiguous 

 to the upper perceptive layer undergoes contraction, while 

 those contiguous to the lower perceptive layer undergoes 

 expansion. 



