They show that the peculiarities are
individual, and that each specimen has its own characters. It is very
probable that a comparative experimental study will prove the existence
of a large number of elementary species, differing in many points; they
will probably also show differences in the amount of the active chemical
substances, especially of emetine, which is usually recorded as present
in about 1%, but which will undoubtedly be found in larger quantities in
some, and in smaller quantities in other elementary species. In this way
the close and careful distinction of the really existing units might
perhaps prove of practical importance.
MacFarlane has studied the beach-plum or _Prunus maritima_, which is
abundant along the coast regions of the Eastern States from Virginia to
New Brunswick. It often covers areas from two to two hundred acres in
extent, sometimes to the exclusion of other plants. It is most prolific
on soft drifting sand near the sea or along the shore, where it may at
times be washed with ocean-spray. The fruit usually become ripe about
the middle of August, and show extreme [57] variations in size, shape,
color, taste, consistency and maturation period, indicating the
existence of separate races or elementary species, with widely differing
qualities. The earlier varieties begin to ripen from August 10 to 20,
and a continuous supply can be had till September 10, while a few good
varieties continue to ripen till September 20.
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