190
LIFE MOVEMENTS IN PLANTS
water, the variation of temperature should not be too sudden; it should commence with tepid, and end with. warm water. Sudden application of hot water brings about certain complications due to excitatory effect. As regards the per- sistence of after-eti'ect of a single application of warm water, it. should be remembered that the absorbed water gradually cools down. In an experiment with a peduncle of Zep/ryrrmé/ms tho growth under partial drought was found to be (Hit ,1. per second ; application of warm water increased the growth rate to 0'20 [1. per second. After 15 minutes the growth rate fell to 0'13}; per second; and after an hour to (NH ,1. INT second. It will be noted that even then the rate was twice the initial rate before irrigation.
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TABLE NILMEI’I’EWI HF IRRIGATION.
Specimen. (’mnllt'ul):v”f EH” “- Rate of growth. nt. l I l i [Cg/sour ' Dry soil 0'21 [L per second. I rrigation with Gold , i \V'Itit'l‘ 0'30 a .. .. Irrigation with warm i \Vntl‘l‘ ... ... 1‘33 )1. ,. ,, I’vdunclo of er/Iy-E Dry soil 0'04 [1. ,, ,, rant/um. Irrigation with warm I; water 0°20 IL ,, ,,
EFFECT OF ARTIFICIAL INCREASE 0i“ INTERNAL HYIHtOS'I‘ATIC PRESSURE.
Increasnd turgor was, next, artificially induced by increase of internal hydrostatic pressure.
hirperiment 71.-—-'l‘hv plant was mounted water-tight in tIu- short limb of an U-tube, and subjected to increased hydrostatic pressure by increasing the height of the water