56 



LIVING PLANTS 



A careful analysis 

 of the above reac- 

 tions will yield many 



interesting re s u 1 1 s . 

 If a quick snip is giv- 

 en with scissors 

 to the terminal 

 pair of pinnules 

 in one of the upper 

 leaves, the pinnules 

 disturbed will close 

 rapidly and then the 

 other pairs will react 

 in succession until 

 the base of the leaflet 

 is reached. After a 

 short interval the 

 basal pairs of pin- 

 nules of the neigh- 

 boring leaflets close 

 and thepairs toward 

 the apices in succes- 

 sion. Before the mo- 

 tion has been taken 

 up by all of the leaf- 

 lets the pulvinus at 

 the base of the 



Fig. 7. — Successive positions of mimosa after stimulation at 

 the tip of a leaflet, a, position a few seconds after a flame is 

 applied at /. b, the impulse has reached the base of the leaf, 

 c, the impulse has traversed nearly the entire shoot and isnear- 

 ing the leaf-tips of the last leaf reached. 



