Petiole-Pulvinus Preparations of Mimosa pudica. 229 



transmitted excitation, which would give rise to an enhanced response of| the 

 motile indicator. In fig. 13 are given two records, (1) before and (2) after the 



Fig. 13. — Action of glycerin in enhancing the speed and intensity of transmitted 



excitation. 



application of glycerin on a length of petiole through which excitation was 

 being transmitted. The time-records demonstrate conclusively the enhanced 

 rate of transmission after the application of glycerin. The increased intensity 

 of transmitted excitation is also seen in the enhanced amplitude of response. 



Action of Injury on Normal Specimens. — A cut stem with entire leaf was 

 taken, and stimulus applied at a distance of 15 mm. from the pulvinus. 

 From the normal record (1) in fig. 14 the velocity of transmission was found 

 to be 187 mm. per sec. The end of the petiole beyond the point of 



Fig. 14. — Effect of injury, depressing rate of conduction in normal specimen ; (1) record 

 before, and (2) after injury. (Intervals, 0"1 sec). 



application of the testing stimulus was now cut off, and record of velocity 

 of transmission taken once more. It will be seen from record (2) that 

 the excessive stimulus caused by injury had induced a depression in the 

 conducting power, the velocity being reduced to lf>7 mm. per sec. Excessive 



