The belief now alluded to has been held in relation to the human species also, and it is affirmed that both the bodily and mental qua lities of the offspring suffer gradual and pro gressive injury from the continued mixture of successive generations of the same family or a small number of families. Hence we find that the marriage of cousins-german, which is according to law in this country, is repro bated as prejudicial by some; and various royal families and aristocratic families are re ferred to as examples of the bad effect of the restriction of conjugal union to a narrow circle.
It must be remembered, however, that the mutual selection of the parents is not quite the same in the human species as among the lower animals ; and in the examples just referred to we feel even inclined to doubt whether, when due allowance is made for the nature of their education, it will be found that kings or princes have become worse or less talented in modern than in ancient times, or whether among that class there is, on en average, a greater proportion of stupid men than in other ranks of society.
The regularity of feature and beauty of the Persian race has been greatly improved by their choice of the most beautiful Circassian and Georgian wives ; and there are many examples of particular families in this country in which regular and handsome features and a •ell-knit and fully developed form of body are hereditary. We shall not pursue the at tempt, however, which some have made to apply the principles of cattle-breeding to the human species ; for however desirable and necessary an improvement of the breed may appear to some Utopian philanthropists, we fear that the mind, with all its peculiar tastes, prejudices, and passions, has too much to do with the greater number of matrimonial al liances to allow physiological considerations much jurisdiction.
From the different facts now touched upon, it is obvious that the original type of the parents modifies that of their offspring; while, in gene ral, varieties accidentally acquired do not pass in hereditary descent, unless they are of such a nature as to constitute a permanently distinct race or variety.
In the mixture of different races of the human species and of distinct species of animals we recognise a constant tendency in succeeding generations to return to the original type or pure breed ; • an effect which seems to proceed natu rally from the general law already announced, that the purer the breed of either of the parents, or in other words, the more nearly it approaches the original type or unmixed race, the more readily will its qualities descend to the off spring. When the mixed offspring of the black
and white races of men unites with either the black or the white, the offspring in successive generations becomes more and more nearly allied to the pure breed with which the cross is made, and at last wholly identified with it. We must look upon this general law of the tendency of all mixed varieties to return to the original type, together with the circumstance that hybrids rarely breed as means adopted by na ture for the preservation of distinct species.
The transmission of hereditary resemblance, either as regards the general structure of the body or peculiarities, is not, however, invari able, nor always immediate from parents to off spring. Thus parents with certain deformities may produce all their children naturally formed and healthy ; or some of them only (in one case the males, in a second the females, in a third some of both sexes) may inherit the ab normal peculiarity, while the rest of the chil dren are healthy. But these healthy children, from some disposition of their constitution, may transmit to their descendants either in the first or in a subsequent generation the defect which existed in their parents. The varieties in this re spect in the human species are almost infinite. 1 hus,in one family all the children resemble one parent in a striking manner ; in another the male children take after the father chiefly, the females after the mother ; and in a third the converse holds, the peculiarities of the father descending principally to daughters, those of the mother to sons,—an arrangement of family resemblance which is the most commonly pre valent according to M. Girou, who endeavours to show that family resemblance frequently passes in an alternating manner from grand parent to grandchild. Thus, the grandchild resembles the grandparent of the same sex, so that a boy whose father is like his (the father's) mother resembles most the grandfather, as in the following plan.