RECORD: Darwin, C. R. & Francis Darwin. [ny].09.19-20. Pistia stratiotes. CUL-DAR209.3.280. Edited by John van Wyhe (Darwin Online, http://darwin-online.org.uk/)
REVISION HISTORY: Transcribed by Christine Chua and edited by John van Wyhe 12.2022. RN1
NOTE: See record in the Darwin Online manuscript catalogue, enter its Identifier here. Reproduced with permission of the Syndics of Cambridge University Library and William Huxley Darwin. The volume CUL-DAR209.3 contains materials for Darwin's book Movement in plants (1880).
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35 Pistia stratiotes— Sep 19 (Temperature varies between 18 1/2 & 23 1/2 C
Glass filament gummed to one leaf– & the angle made by the filament read 14 times between 9 am & 11·50 pm.
Sep 19– 9 am /— 32° above horizon
3.34 pm / 10° above horizon
11.50 pm / 55° above horizon
The angles at 3.34 pm & 11.50 pm were the lowest & highest observed; therefore the leave rises through 45°
On Sep 20th the leaf was 10° above Horizon at 8.25am & remained at about 15° above horizon, till sometime after 3.16 pm; at 5.40 pm when it was next looked at it was 23° above; & at 9.30pm it was 58° above In this case so that the the total rise was on the day 48° from 10° above at 8h 25m am to 58° above at 9.30 pm
On Sep 19th it only rose it did not rise from its lowest point ie 1 10° above hor at all till 4.29 pm & by 4.53 it was only 13° above; when next examined at 5.48 it was 22° above, & at 6.40 33° above, so one may say it began to rise between 5 & 6 I think
Citation: John van Wyhe, ed. 2002-. The Complete Work of Charles Darwin Online. (http://darwin-online.org.uk/)
File last updated 24 January, 2023