vitality in little more than a year. Further, the older the seed the
more slow as a general rule will germination be in starting, but there
are notable exceptions. This pause, often of so long duration, in
the growth of the embryo between the time of its perfect development
within the seed and the moment of germination, is one of the
remarkable and distinctive features of the life of Spermatophytes. The
aim of germination is the fixing of the embryo in the soil, effected
usually by means of the root, which is the first part of the embryo
to appear, in preparation for the elongation of the epicotyledonary
portion of the shoot, and there is infinite variety in the details
of the process. In albuminous Dicotyledons the cotyledons act as the
absorbents of the reserve-food of the seed and are commonly brought
above ground (_epigeal_), either withdrawn from the seed-coat or
carrying it upon them, and then they serve as the first green organs
of the plant. The part of the stem below the cotyledons (_hypocotyl_)
commonly plays the greater part in bringing this about. Exalbuminous
Dicotyledons usually store reserve-food in their cotyledons, which
may in germination remain below ground (_hypogeal_). In albuminous
Monocotyledons the cotyledon itself, probably in consequence of its
terminal position, is commonly the agent by which the embryo is thrust
out of the seed, and it may function solely as a feeder, its extremity
developing as a sucker through which the endosperm is absorbed, or
it may become the first green organ, the terminal sucker dropping
off with the seed-coat when the endosperm is exhausted. Exalbuminous
Monocotyledons are either hydrophytes or strongly hygrophilous plants
and have often peculiar features in germination.

[v.02 p.0013]