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Down Aug 17th. 1877 Horace

Dwarf Kidney Bean — Greenhouse

Observed angles of both parts of petiole of two leaves at 12 midday and at 10. 15 P.M. of two leaves, one very young, & the other fully developed. [Fig]

[Table]

I think that The movement of one part of the petiole relatively to the other is so small (2°1/2 &nd 1 1/4°) that it may be accounted for by errors of observation, especially in the young leaf as the upper part of the petiole was very short. Hence I think we may say that the petiole moves turns upwards as a whole about its lower end, in going to sleep, through 1/4 ° 16 1/4°; I get this for the younger leaf; I get this

[69]

from the differences of the angles of the lower part, as these angle observations were was more reliable that that those of the short upper part.

For the Older leaf, the angle through which it moved up — if we assume that it moved as a whole— is 11°, or 9 1/2° according as we take the angles of lower or upper part of petiole as correct; thus giving equal weight to the two observations, the angle through which it moved up = 11 + 9 1/2 / 2 = 10 1/4°