Page:Life Movements in Plants.djvu/221

in the longer limb. Table XIII shows how increasing pres— sure enhances the rate of growth till a critical point is reached, beyond which there is a depression. This critical point varies in different plants.

TABLE XIII.—EFFECT OF INCREASED INTERNAL “\DRUS'I‘A'I'It‘ PRESSURE

( Kysoor). Specimen. Hydrostatic pressure. Rate of growth.

Normal 0'18 a per second.

i No. I 2 cm. pressure 0'20 ,1. ,, ,,

t 4 cm. ,, 0'11 ’1. ., ,.

Normal 0'13 a ,, ,,

i No. II em. pressure 0-20 ,1. ,, ,,

1 .i cm. ,, 0°18 a ,. ,.

I i 0111. ,, ... “'15” ,, ,,

v _ _ _ --- __

RESPONSE TO NEGATIVE VARIATION OF TURGOIL

I shall now describe the influence of induced diminution of turgor on the rate of growth.

JIM/rod of plasmolgsis: It‘rperin'umt 7.?.--lieing desirous of demonstrating the responsive growth ’ariations of opposite signs in an iden- tical specimen under alternate increase and diminution of turgor, I continued the axperiment with the same peduncle of Zep/aymnt’tes in which the growth acceleration was induced hy irrigation with warm water. In that experiment the growth rate of (HM/1, per second was enhanced to 0‘20 ,1, per second after irrigation. A strong solution of KNO” was now applied at the root;

Fm, 71_.__En‘ect of alternate increase and diminution of turgor on the same specimen : N, normal rate under drought; H, enhanced rate under irrigation'with warm water; N’, normal permanent rate after irrigation; P, diminished rate afterplasmo- lysis (Zephyrantlzes).