the leaf of Minwsa and the movement due to growth,
which is summarized as follows :—
(1) An increaseor positive vm'iation of [my/or in- duces an, erection or positive 'response of the leaf of Mimosa, and (1; positive variation 01‘ (mhancement of the rate of growth.
(2)11 diminution or negative mtriuiimi of larger induces a, fall or negative response of the leaf of Mimosa, and a negative variation or retarda- tion of the rate of growth.
EFFECT OF EXTERNAL TENSION.
Experiment 73.——-The recording lovers are at first so balanced that very little tension is exerted on the plant. Record of normal growth is taken of a specimen of (Irinmn. The tension is gradually increased from one grain to ten grams. The table given above shows how growth—rate in- creases with the tension till a limit is reached, after which there is a retardation.
TABLE XV.—EFFEl‘T ()l“ TENSION ON GROWTH.
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I Tension. Rate of growth.
‘1 0 (Normal) ...i Q41 ,1, per second.
1 4 grams 0'44 [L n n
! 6 ,, 048 ., .,
i 8 H coo cc. .00! H N
no ,, 0-40 .L .. .,
SUMMARY.
Increase of turgor induced by irrigation enhances the rate of growth. Irrigation with warm water induces a further augmentation of the rate of growth.
