Page:Life Movements in Plants.djvu/208

178 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».