After the first two or three days the cotyledons diverge more during the
day and cease to close at night. Those of Trichosanthes anguina are
somewhat thick and fleshy, and did not rise at night; and they could
perhaps hardly be expected to do so. On the other hand, those of
Acanthosicyos horrida* present nothing in their appearance opposed to their
moving at night in the same manner as the preceding species; yet they did
not rise up in any plain manner. This fact leads to the belief that the
nocturnal movements of the above-named species has been acquired for some
special purpose, which may be to protect the young plumule from radiation,
by the close contact of the whole basal portion of the two cotyledons.
Geranium rotundifolium (Geraniaceae).--A single seedling came up
accidentally in a pot, and its cotyledons were observed to bend
perpendicularly downwards during several successive nights, having been
horizontal at noon. It grew into a fine plant but died before flowering: it
was sent to Kew and pronounced to be certainly a Geranium, and in all
probability the above-named species.
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