VELOCITY OF TRANSMITTED IMPULSE 137 



vigorous. The distance at which the stimulus was applied 

 was 30 mm. from the responding pulvinus, and the inten- 

 sity of stimulus was 3 units. The frequency of the vibrat- 

 ing-recorder was 10 per second ; hence the distance between 

 any two successive dots in the record represents a time- 

 interval of one-tenth of a second, and from the record 

 itself it will not be found difficult to estimate intervals of 

 even one-fifth that amount. The lowest of the three records 

 in fig. 82 represents the results of the first experiment. It 

 will be seen that the interval between the stimulus and the 



Fig. 82. — Determination of velocity of transmission of excitation 

 in Mimosa. Two lower records are in response to stimulus 

 applied at a distance of 30 mm. ; upper record in response 

 to direct stimulation giving the latent period. Recorder 

 10 D.V. 



beginning of response is i6 - 2 spaces, each of the value of 'i 

 second. Therefore the total time T is 1/62 second. After a 

 suitable interval necessary for complete recovery of con- 

 ductivity, a second record was taken, under the same con- 

 ditions, on the same plate. The minimum interval necessary 

 varies from 15 to 20 minutes, depending on the condition 

 of the specimen and the season. It will be seen that the 

 time-interval in this case is the same as before — namely, 

 1*62 second. The third record was taken with direct stimu- 

 lation, and from this it will be noted that the latent period 



