. Hydration and growth. Growth (Plants); Plants. Imbibition and Growth of Opuntia. 135 tion or absorption action of the plasmatic colloids, which in the case of Opuntia are probably low in proteins.^ The growth of etiolated shoots of Opuntia is of an indefinite char- acter, as the length which such members may reach depends to a large extent upon the amoxmt of available material and other features. Shoots which were already a few weeks old, and which had developed in a dark chamber kept at 16° to 18° C. were found to be growing at the rate of mm. daily. These were removed to a second chamb
. Hydration and growth. Growth (Plants); Plants. Imbibition and Growth of Opuntia. 135 tion or absorption action of the plasmatic colloids, which in the case of Opuntia are probably low in proteins.^ The growth of etiolated shoots of Opuntia is of an indefinite char- acter, as the length which such members may reach depends to a large extent upon the amoxmt of available material and other features. Shoots which were already a few weeks old, and which had developed in a dark chamber kept at 16° to 18° C. were found to be growing at the rate of mm. daily. These were removed to a second chamber, in which the temperature was kept steadily at 16° C. for 3 days, during which time the rate varied from mm. to mm. daily. The temperature was brought up to 21° to 23° C. in 3 hours, and the rate was 5 nun. for the first day. During the second and third days at this temperature the rate rose to 7 mm. per day. The rate was mm. daily during the next 2 days and about 8 mm. daily for a final period of 16 hom-s. The temperature now being raised to 30° C. m 2 hours, and after that varying from 30° to ° C, the rate was 11 mm. daUy during the first 16 hours, then at the rate of mm. during the succeeding 12 hours, during which time the elongation pro- gressed in a remarkably imiform manner. 468 10 m. 2460 Fig. 24.—Auxographic record of varia- tions of length of etiolated shoot of Opuntia X26, at temperatures as be- low , sheet ruled to 10 mm. intervals: (a) downward movement of pen 7''30™ a. m. to 9''40" a. m. denoting growth at tem- peratures of the stem of 45° to 49° C.; (6) growth checked for 20 minutes at 49° C.; (c) growth resumed at temper- ature of 49° C; (d) shortening at ° to 52° C; (e) stationary at ° C; (/) growing at temperatures of 48° to 49° C; (ff) shortening at 49° C; (h) growing at 38° to 41° C.; (i) shorten- ing at 49° C. The rate itself was one which might have been identified with that of a
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectplants, bookyear1920
