Page:Researches on Irritability of Plants.djvu/80

Rh and in the last it was made 2000 mgrms. Successive records were made, for purposes of comparison, on the same part of the plate. The vertical lines under the diagram (fig. 26) are time-marks, indicating intervals of one minute. It will be seen that the height of the record, with a load of 100 mgrms. is the greatest of the three, being 41 mm. The recovery was completed in this case after the expiration

of 9 minutes. The height of the second, under a load of 500 mgrms. is 28 mm., but recovery is nearly complete in 6.5 minutes. And, finally, with the load of 2000 mgrms. the height is the least, being 13 mm., but the recovery is seen to be completed in 5 minutes. Thus the effect of load in the contractile response of the plant is shown to be strictly parallel with its influence on the contractile response of animal muscle.

The motile tissue of the plant, like that of the animal, is capable of doing work during excitatory movement. The influence of load on the height and period of response