Only partial
or vegetative variability is present. Unfertilized eggs when developing
into embryos are equivalent to buds, separated from the parent-plant and
planted for themselves. They repeat both the specific and the individual
characters of the parent. In the case of the hawkweed and the dandelion
there is at present no means of distinguishing between these two
contrasting causes of variability. But like the garden varieties which
are always propagated in the vegetative way, their constancy and
uniformity are only apparent and afford no real indication of hereditary
qualities.
In addition to these and other exceptional cases, seed-cultures are
henceforth to be considered as the sole means of recognizing the really
existing systematic units of nature. All other groups, including
systematic species and [62] genera, are equally artificial or
conventional. In other words we may state "that current misconceptions
as to the extreme range of fluctuating variability of many native
species have generally arisen from a failure to recognize the composite
nature of the forms in question," as has been demonstrated by MacDougal
in the case of the common evening-primrose, _Oenothera biennis_. "It is
evident that to study the behavior of the characters of plants we must
have them in their simplest combinations; to investigate the origin and
movements of species we must deal with them singly and uncomplicated.
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