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Rh ment of the stigma of the flower from which the pollen came; if another combination is made, either naturally or by artificial fertilisation, then, if a result follows at all, the seedlings are scanty, dwarfed and sometimes infertile, much as when hybrids between species are formed.

It is to be noticed that the authors who have discussed heterostylism are not satisfied with the usual explanation, which is that the insects which visit the flowers carry the pollen at different relative positions on their bodies corresponding to the different lengths of the sexual organs and so produce the wonderful result. Darwin, moreover, admits that bees carry all sorts of pollen on every part of their bodies; so that it has still to be made clear how the female organs dusted with two or three kinds of pollen make their choice of the most suitable. The supposition of a power of choice, however interesting and wonderful it is, does not account for the bad results which follow artificial dusting with the wrong kind of pollen (so-called "illegitimate fertilisation"). The theory that the stigmas can only make use of, or are capable of receiving only "legitimate pollen" has been proved by Darwin to be erroneous, inasmuch as the insects which act as fertilisers certainly sometimes start various cross-breedings.

The hypothesis that the reason for this selective retention on the part of individuals is a special quality, deep-seated in the flowers themselves, seems more probable. We have probably here to do with the presence, just as in human beings, of a maximum degree of sexual attraction between individuals, one of which possesses just as much femaleness as the other possesses maleness, and this is merely another mode of stating my sexual law. The probability of this interpretation is increased by the fact that in the short-styled, long-anthered, more male flowers, the pollen grains are larger and the papillae on the stigmas are smaller than the corresponding parts of the long-styled, short-anthered, more female flowers. Here we have certainly to do with different degrees of maleness and femaleness. These circumstances supply a strong corroboration of my law of sexual affinity,