[page 106]
allowed to germinate in damp air, and now a thin flat disc was developed
all round the base of the hypocotyl and grew to an extraordinary breadth,
like the frill described under Mimosa, but somewhat broader. Flahault says
that with Mirabilis, a member of the same family with Abronia, a heel or
collar is developed all round the base of the hypocotyl, but more on one
side than on the other; and that it frees the cotyledons from their
seed-coats. We observed only old seeds, and these were ruptured by the
absorption of moisture, independently of any aid from the heel and before
the protrusion of the radicle; but it does not follow from our experience
that fresh and tough fruits would behave in a like manner.
In concluding this section of the present chapter it may be convenient to
summarise, under the form of an illustration, the usual movements of the
hypocotyls and epicotyls of seedlings, whilst breaking through the ground
and immediately afterwards. We may suppose a man to be thrown down on his
hands and knees, and at the same time to one side, by a load of hay falling
on him.
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