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PHOTOSYNTHETIC RECORDER
quickened. The plant is such a sensitive detector of light that it may be employed as a photometer for indicating the slightest variations in the intensity of skylight.
The Hourly Variation of Assimilation
For this determination I took successive records from 7-30 a.m. until 5 p.m. for five minutes at a time. When the sun rose at 6-45 a.m. the light was too feeble to be effective. At 7-30 a.m. assimilation began, and the plant evolved four bubbles of oxygen in the course of five minutes; with the progress of the day it became
Fig. 105. Automatic Records of successive Bubblings for five minutes during different periods of the day.
Note the slow rate at 7-30 a.m. and 4-30 p.m., and the quick rate at mid-day.
