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44 of the progeny, which must be treated with bromide and other drugs. So, also, the degeneration of modern Jews may be traced in part to the fact that amongst them marriages for other reasons than love are specially common.

Amongst the many fundamental principles established by the careful observations and experiments of Darwin, and since confirmed by other investigators, is the fact that both very closely related individuals, and those whose specific characters are too unlike, have little sexual attraction for each other, and that if in spite of this sexual union occurs, the offspring usually die at an early stage or are very feeble, or are practically infertile. So also, in heterostylous plants "legitimate fertilisation" brings about more numerous and vigorous seeds than come from other unions.

It may be said in general that the offspring of those parents which showed the greatest sexual attraction succeed best.

This rule, which is certainly universal, implies the correctness of a conclusion which might be drawn from the earlier part of this book. When a marriage has taken place and children have been produced, these have gained nothing from the conquest of sexual repulsion by the parents, for such a conquest could not take place without damage to the mental and bodily characters of the children that would come of it. It is certain, however, that many childless marriages have been loveless marriages. The old idea that the chance of conception is increased where there is a mutual participation in the sexual act is closely connected with what we have been considering as to the greater intensity of the sexual attraction between two complementary individuals.