DETERMINATION OF THE LATENT PERIOD 119 



same specimen, using the same stimulus but varying the 

 mode of record — that is to say, the vibrator used in one 

 case had been tuned to 50 vibrations per second, the length 

 of the recorder being 12 cm. The speed of the recording- 

 plate was in this case relatively slow. The result is shown 

 in fig. 71. The other record in fig. 72 was taken immediately 

 afterwards from the same specimen with a vibrator tuned 

 to 100 double vibrations per second, the recording-plate 



Figs. 71, 72. — Two successive records taken with the same leaf; upper 

 with 50 D.V. recorder and slow-moving plate ; lower with 100 D.V. 

 recorder and faster-moving plate. Latent period in either case is 

 •17 second, proving that value of L is unaffected by any peculiarity of 

 the recorder. 



moving at a faster rate. It will be seen from fig. 71 

 that the time-interval in the first case is represented by 

 8*5 spaces, each representing -02 second, therefore proving 

 the latent period L to be -17 second. This, it should be 

 mentioned, was an autumn specimen, in which the latent 

 period is somewhat longer than in summer. In the second 

 record, fig. 72, under its different speed and with the vibrator 

 giving 100 vibrations per second — we find the intervening 

 spaces to be 17. This gives the latent period as again 



