Page:Researches on Irritability of Plants.djvu/152

Rh intensity 3. This is the intensity which is always used unless the contrary be stated. In order to exhibit the effect of fatigue, the second record is taken after a period of rest of only 15 minutes. The upper record (vibration-frequency 100) gives the normal value of L to be .11 second; the lower record shows that the latent period has been prolonged to .16 second on account of fatigue (fig. 78).

The experiment was repeated with a different specimen and with a vibrating recorder giving 50 vibrations per second. The record (fig. 79) shows again that the latent period is prolonged under fatigue, from the normal .1 second to .14 second. The effect of fatigue is independently seen in the record, in the relative sluggishness of the responsive movement. The slope in the response of the fresh specimen is almost vertical, with successive dots very widely spaced. In the response of the fatigued specimen a great contrast is observed in both these respects.

I give below a tabular statement showing results of different experiments on the effect of fatigue:—