Page:Life Movements in Plants.djvu/208

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178
LIFE MOVEMENTS IN PLANTS


In some plants the optimum is reached at about 28 C, and the rate remains constant for the next 10 degrees or. more.

We. at. Fm. 6:3.

FIG, l”. "li'W‘lH'll Hf l-lro'l‘l Ul- Hf ll'lllln'l'llllll‘t: from to arrest 0f EgrOWtil at 22’l'. l"|1:.li.'l. «Hill-rt of ri~e of temperature from 53’0 to MPG. A sudden

Conlrartinn, indicativv of IllIRlll-Sllllhill, lakes place at tiO’C.

’l’vmpamlm'c mmrinmm: lulz'pm'inmnt 60.—-For the deter- mination of the maximum, the tmnperature was raised much higher. At .35 (‘. growth was found to he greatly retarded with practical :trrefit at :38 (3. At 60 (J there occurred a sudden apasmollic contraction (Fig. 65), which I have shown elsewhere to he the spamn of death. This mechanical spasm at till (‘ is also strikingly shown by various pulvinat- ed organe. An electrie Spasm of galvanometric negativity, and a sudden diminution of electrical resistance also take place. at th‘ critical temperature of 60‘0.‘

l have dusrrlln-tl the immediate effect at the critical point. Loni: maintenance at a temperature. few degrees

‘ Bosh: —“ Plant Itespnli~u-."p 168: " Comparative Eh-ctro-Physiology," p. 202, p- blf».