, became
hooked, and a seventh formed a complete loop, when first looked at after 15
hours.
The accompanying figures of four germinating seeds (Fig. 69) show, firstly,
a radicle (A) the apex of which has become so much bent away from the
attached square as to form a hook. Secondly (B), a hook converted through
the continued irritation of the card, aided perhaps by geotropism, into an
almost complete circle or loop. The tip in the act of forming a loop
generally rubs against the upper part of the radicle, and pushes off the
attached square; the loop then contracts or closes, but never disappears;
and the apex afterwards grows vertically downwards, being no longer
irritated by any attached object. This frequently occurred, and is
represented at C. The jar above mentioned with the six hooked radicles and
another jar were kept for two additional days, for the sake of observing
how the hooks would be modified. Most of them became converted into simple
loops, like that figured at C; but in one case the apex did not rub against
the upper part of the radicle and thus remove the card; and it consequently
made, owing
[page 179]
to the continued irritation from the card, two complete loops, that is, a
helix of two spires; which afterwards became pressed closely together.
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