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with sleeping plants the rate and amplitude of the movements of the
leaves have been so far modified in relation to light, that they move in a
certain direction with the waning light of the evening and with the
increasing light of the morning more rapidly, and to a greater extent, than
at other hours.
But the leaves and cotyledons of many non-sleeping plants move in a much
more complex manner than in the cases just alluded to, for they describe
two, three, or more ellipses in the course of a day. Now, if a plant of
this kind were converted into one that slept, one side of one of the
several ellipses which each leaf daily describes, would have to be greatly
increased in length in the evening, until the leaf stood vertically, when
it would go on circumnutating about the same spot. On the following
morning, the side of another ellipse would have to be similarly increased
in length so as to bring the leaf back again into its diurnal position,
when it would again circumnutate
[page 411]
until the evening. If the reader will look, for instance, at the diagram
(Fig.


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