[15]

(12

Cassia

 Dec. 24'. Brought plant from warm greenhouse into study yesterday at midday & today (Temp of Study 54°-56°, perhaps too cold for spont., movements) & observed movements of tips of leaf on glass-plate. Began at 8° A.m, when just light. Leaf in nearly the same position to light as on previous days — Day rather clear. —Two leaves observed. First terminal leaflet rather torpid leaf pointed almost directly from light, yet slightly there was inclination which determined lateral movement to one side. This leaflet moved obliquely downwards until 9° 5, & then bent to right hand still descending a little until 9° 33'; then, bent suddenly to left, still descending very little until 1° 5', when it bent to right side still slightly descending until 2° 40° or 3°, when it began to rise again until 4°but this latter movement was confused by leaf beginning to go to sleep.

The second leaflet, descended perpendicular during same time & rather irregularly in later or lower parts of course, & begin ascending again a little to right-hand of its downward course. Case vy like that of Oxalis senitiva. It seems that the upward night movement is counteracted by slow downward movement during greater part of day, but that before night upward movement recommences. See

[15v]

what I say under Oxalis — The course traced onto glass is a vertical very irregular ellipse,— Much modified by the side at which light comes. The first leaf by rising upwards wd. have approached the light far more effectually from its position that it did by lateral movement but the force of light was by no means sufficient to overcome the downward movement which counteracts the previous upward movement of sleep.—