15 m. With Solanum lycopersicum
the cotyledons, after falling in the forenoon, zigzagged from side to side
between 12 and 4 P.M., and then commenced rising. The cotyledons of Lupinus
luteus are so thick (about .08 of an inch) and fleshy,* that they seemed
little likely to move, and were therefore observed with especial interest;
they certainly moved largely up and down, and as the line traced was zigzag
there was some lateral movement. The nine cotyledons of a seedling Pinus
pinaster plainly circumnutated; and the figures described approached more
nearly to irregular circles than to irregular ovals or ellipses. The
sheath-like cotyledons of the Gramineae circumnutate, that is, move to all
sides, as plainly as do the hypocotyls or epicotyls of any dicotyledonous
plants. Lastly, the very young fronds of a Fern and of a Selaginella
circumnutated.
In a large majority of the cases which were carefully observed, the
cotyledons sink a little downwards in the forenoon, and rise a little in
the afternoon or evening. They thus stand rather more highly inclined
during the night than during the mid-day, at which
* The cotyledons, though bright green, resemble to a certain extent
hypogean ones; see the interesting discussion by Haberlandt ('Die
Schutzeinrichtungen,' etc.
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