It is the more remarkable, because we shall meet with
an analogous case in the leaves of the allied genus Melilotus, in which the
terminal leaflet rotates at night so as to present one edge to the zenith
and at the same time bends to one side, so that its upper surface comes
into contact with that of one of the two now vertical lateral leaflets.]
Concluding Remarks on the Nyctitropic Movements of Cotyledons.--The sleep
of cotyledons (though this is a subject which has been little attended to),
seems to be a more common phenomenon than that of leaves. We observed the
position of the cotyledons during the day and night in 153 genera, widely
distributed throughout the dicotyledonous series, but otherwise selected
almost by hazard; and one or more species in 26 of these genera placed
their cotyledons at night so as to stand vertically or almost vertically,
having generally moved through an angle of at least 60o. If we lay on one
side the Leguminosae, the cotyledons of which are particularly liable to
sleep, 140 genera remain; and out of these, the cotyledons of at least one
species in 19 genera slept.
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