Lotus Jacoboeus (Leguminosae).--The cotyledons of this plant, after the few
first days of their life, rise so as to stand almost, though rarely quite,
vertically at night. They continue to act in this manner for a long time
even after the development of some of the true leaves. With seedlings, 3
inches in height, and bearing five or six leaves, they rose at night about
45o. They continued to act thus for about an additional fortnight.
Subsequently they remained horizontal at night, though still green
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and at last dropped off. Their rising at night so as to stand almost
vertically appears to depend largely on temperature; for when the seedlings
were kept in a cool house, though they still continued to grow, the
cotyledons did not become vertical at night. It is remarkable that the
cotyledons do not generally rise at night to any conspicuous extent during
the first four or five days after germination; but the period was extremely
variable with seedlings kept under the same conditions; and many were
observed. Glass filaments with minute triangles of paper were fixed to the
cotyledons (1 ½ mm. in breadth) of two seedlings, only 24 h. old, and the
hypocotyl was secured to a stick; their movements greatly magnified were
traced, and they certainly circumnutated the whole time on a small scale,
but they did not exhibit any distinct nocturnal and diurnal movement. The
hypocotyls, when left free, circumnutated over a large space.

Another and much older seedling, bearing a half-developed leaf, had its
movements traced in a similar manner during the three first days and nights
of June; but seedlings at this age appear to be very sensitive to a
deficiency of light; they were observed under a rather dim skylight, at a
temperature of between 16o to 17 1/2o C.' and apparently, in consequence of
these conditions, the great daily movement of the cotyledons ceased on the
third day. During the first two days they began rising in the early