In the second experiment the records (Fig. 820) were taken on a moving plate. The Specimen was so extremely sub- tonic, that its normal record N appears almost horizontal. The greater erection of the curve, S, after stimulation demonstrates the induced acceleration of growth.
TABLE XX.—"AC(,‘ELERATIUN OF GROWTH BY STIMULUQ IN SUB-'I'ONIC SI’EJIMESS.
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Specimen. 1 Stimulus. Rate of growth.
Wheat seedling ' Normal 0'05 ,1, per sec. {
After electric stimulation 0-12 ,1 ,, ,, l
[Cg/sour Normal 0'30 ,1 per see. I ' After 5' exposure to light 0'40 ,u. ,, ,, H ,9 H l P‘ H ’9
In my previous Paper on the ‘Modifying Influence of Tonic ,‘ondition’ I showed that while the response of the primary pulvinus of Mimosa in normal condition is Negative, i.e., by contraction, diminution of turgor, and fall of the leaf, the response of a sub-tonic specimen is positive, that is to say, by expansion, enhancement of turgor, and erection of the leaf. I have shown further that in a sub-tonic specimen the action of stimulus itself raises the, tissue. from below par to normal or even above par, with the conversion of abnormal positive to normal negative response.
I have in the present Paper shown that a parallel Series of reactions is seen in the reSponse of growing organs. In vigorously growing specimens the action of stimulus is .mgtztum, i.e., incipient cont‘action, diminution of turgor, and retardation of the Me of growth. But in sub-tonic Specimens, with enfeebled rate. of growth, the effect of
