Page:Researches on Irritability of Plants.djvu/144

Rh period shorter than .08 second or longer than .12 second in summer may be regarded as rather exceptional.

The shortest latent period that I have come across is .06 second obtained in summer and when the temperature was specially high. The longest in summer was .14 second. Most specimens have a latent period not appreciably differing from .1 second. This may be regarded as approximately the average value for summer. In winter and with sluggish specimens the latent period may be prolonged to a value of something like twice as much, that is to say, .2 second, more or less.

Latent period of Mimosa may be determined with great accuracy by means of Resonant Recorder. This enables the measurement of time-interval shorter than .005 second.

Error due to inertia is reduced to a minimum on account of extreme lightness of plant-recorder, which is nearly a hundred times lighter than muscle-recorder.

Successive values of latent period with the same specimen are found to be constant. The results are not modified by employment of different recorders.

The shortest value of latent period given by a vigorous Mimosa leaf in summer is .06 second, the average value being .1 second.

The latent period of leaf of Neptunia oleracea is .6 second.