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Passing on now to apogamy, or isolation of the indiscriminate kind, we may well be disposed, at first sight, to conclude that this kind of isolation can count for nothing in the process of evolution.

The last-mentioned case has been regarded as representing an apogamous development of the sporophyte from the gametophyte comparable to the cases of apogamy described in Ferns.

And, of course, as soon as this change of type begins, the isolation ceases to be indiscriminate: the previous apogamy has been converted into homogamy, with the usual result of causing a divergence of type.

It was in order to recognize this additional and very important factor that I chose the name Independent Variability whereby to designate the diversifying influence of merely indiscriminate isolation, or apogamy.

Except where very large populations are concerned, indiscriminate isolation always tends to become increasingly discriminate; and, in the measure that it does so, apogamy passes into homogamy, by virtue of Independent Variability.