=Selection by marriage has the last word.=--It follows, then, though the fact is almost constantly ignored by eugenic writers, that selection by marriage in effect has the last word. Thus supposing that all other forms of selection, depending upon, for instance, the various causes of death amongst the immature, were what we call reversed selection; or supposing that, as is actually the case, society permitted large numbers of the so-called unfit to survive,--even so, marriage selection (if it meant that many or most of these were rejected by it) would control and correct the dangerous tendency. On all hands, scientific and unscientific, we have writers telling us of the disastrous multiplication of the unfit. Such multiplication does occur and is disastrous. Yet hitherto they have failed to recognise that if--to take an extreme case--all these unfit are rejected by marriage selection--that is to say, do not themselves become parents--this alarming multiplication is, after all, not a persistent factor in racial change, but merely the throwing up or throwing aside in each generation of a certain number of undesirables _whose breed gets no further_. Of course there would be much less urgent need for eugenics if this last were wholly and happily the case. Our object, indeed, is to make it the case: but so long as selection by marriage exists,--and its occurrence is palpably indisputable--_it is a serious flaw in the common argument to assume that the production and preservation of undesirables necessarily involves their own parenthood in due course_. It is necessary that strict statistical enquiry be made on this point. It would show, I believe, that the marriage-rate _and the birth-rate_ amongst the _grossly_ unfit is much lower than that of the general community, or, in other words, that the influence and value of selection by marriage (which, as we have shown, is in effect selection for parenthood, the only selection that ultimately matters) has not yet been fully appreciated. I very strongly incline to the view that if this protective factor were not constantly at work, the “multiplication of the unfit” would long ago have led to the destruction of every civilised nation on the earth: they would have swamped us long ago. Indeed, the proposition may be laid down that, supreme and indispensable as are the services of marriage to race-culture, in its protection of motherhood, and the support of motherhood by fatherhood, probably the services of marriage as in effect the working of sexual selection are worthy of being rated almost, if not quite, as high.