Dion era Muscipuia, Ellis. 



after contact, so that some molecular disturbance is being 

 propagated through the leaf substance, though not for the 

 time producing very manifest results. 



Experiments were conducted to ascertain the length <>f time 

 which can intervene between first and second stimulus, bet 

 the impression of the first was lost. In other words, the mem- 

 ory power of the protoplasm was tested. On bright da 

 with temperature at 6$°-y2° F. in a cool house, healthy speci- 

 mens were selected. A leaf hair was stimulated once but the 

 leaf did not close. A second stimulus after ten seconds 

 caused closure with a latent period of less than two seconds. 

 Another leaf was once stimulated, and after an interval of 

 thirth-five seconds a second stimulus was applied when the 

 leaf closed rather slowly. A rather small leaf was restimu- 

 lated after lapse of twenty-five seconds, and a slight degree 

 of closure occurred. A third shock was given after thirty 

 seconds which caused closure to about one-third of its extent. 

 A fourth shock after twenty seconds produced further closure, 

 and after lapse of ten seconds a fifth shock completed the 

 process, though the movement of the halves was slow and 

 deliberate, about fifteen seconds being required. 



Three leaves were operated on by stimuli at intervals of 

 thirty seconds, and after the third stimulus no closure-effect 

 was observable, but when the time-interval was reduced to 

 twenty seconds two successive shocks closed two of the leaves, 

 and another shock after ten seconds closed the third. All of 

 the above were smaller leaves, by about half, than the average 

 size attained in the wild state in North Carolina, and leaves 

 were therefore chosen nearly like the latter. A large healthy 

 leaf was acted on as follows : 



ist stimulus no effect. 



z<\ " after sixty seconds, " 



3d 



4th " 



5th " " fifty " extremely slight closure. 



6th " " " " decided closure to extent of 



about half. 



7th " " " " closed loosely, and moved in 



doing so for eighteen sec- 

 onds. 



