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Thus, one leaf descended during the first two nights
(i.e. between 10 P.M. and 7 A.M. next morning) instead of ascending, and on
the third night it moved chiefly in a lateral direction. The second leaf
behaved in an equally abnormal manner, moving laterally during the first
night, descending greatly during the second, and ascending to an unusual
height during the third night.
With plants kept at a high temperature and exposed to the light, the most
rapid circumnutating movement of the apex of a leaf which was observed,
amounted to 1/500 of an inch in one second; and this would have equalled
1/8 of an inch in a minute, had not the leaf occasionally stood still. The
actual distance travelled by the apex (as ascertained by a measure placed
close to the leaf) was on one occasion nearly 3/4 of an inch in a vertical
direction in 15 m.; and on another occasion 5/8 of an inch in 60 m.; but
there was also some lateral movement.
Mimosa albida.*--The leaves of this plant, one of which is here figured
(Fig. 159) reduced to 2/3 of the natural size, present some
Fig.


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