(Vienna),
Jan. 17th, 1878. Also published separately, see p. 32.
[page 100]
cotyl, with the two legs fixed in the ground, certainly circumnutates, and
as it consists of a single internode, we may conclude that it grows in the
manner described by Wiesner. It may be added, that the crown of the arch
does not grow, or grows very slowly, for it does not increase much in
breadth, whilst the arch itself increases greatly in height.
The circumnutating movements of arched hypocotyls and epicotyls can hardly
fail to aid them in breaking through the ground, if this be damp and soft;
though no doubt their emergence depends mainly on the force exerted by
their longitudinal growth. Although the arch circumnutates only to a slight
extent and probably with little force, yet it is able to move the soil near
the surface, though it may not be able to do so at a moderate depth. A pot
with seeds of Solanum palinacanthum, the tall arched hypocotyls of which
had emerged and were growing rather slowly, was covered with fine
argillaceous sand kept damp, and this at first closely surrounded the bases
of the arches; but soon a narrow open crack was formed round each of them,
which could be accounted for only by their having pushed away the sand on
all sides; for no such cracks surrounded some little sticks and pins which
had been driven into the sand.
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