Page:Life Movements in Plants.djvu/219

Rh Kysoor which had been dug up with an attached quantity of soil; this latter was enclosed in a small bag. The plant was then securely clamped and fixed on a stand. This precaution was taken to prevent upward displacement. by the swelling of the soil in ﬂower pot of the. plant under irrigation. The Specimen was then subjected to a condition of drought, water being withheld for a day. The depressed rate of growth is seen in record (Fig. 70). Ordinary cold water was now applied at the root, the effect of which is seen in record 0. Finally the record (ll) was obtained after irrigation with tepid water. It will be seen that the spaces between successive dots, representing magni- tied growth at intervals of ten seconds, are very different. While a given elongation took place under drought in 19x10 seconds, a similar lengthening took place, after irrid gation with cold water, in 13x10 seconds, and after irrigation with warm water in 3x10 seconds. Irrigation with warm water is thus seen to increase the rate of growth more than six times.

Flu, 7tl.~-l‘}ll'cct of irrigation: l), record of growth under drought; (I. acceleration after irrigation \\ll.ll(3(ll(l “ater; ll, enhanced acceleration on irrigation uith warm water. (S. Ail/mar.)

The enhancement of the rate of growth on irrigation with cold water took place after seventy seconds. The interval will obvioust depend on the distance between the root by which the water is absorbed and the region of growth. It will further depend on the activity of the process of the ascent of sap. The time interval is greatly reduced when this activity is in any way increased. Thus the responsive growth elongation after application of warm water was very much quicker; in the case described it was less than 20 seconds. With regard to application of warm