Sir

I hope that you will excuse the liberty which I take in addressing you on a subject which I believe to be of scientific importance, & which you might greatly aid, if you sh^d think fit, to give the [illeg] after consulting those competent to form an opinion.— I have been led to study experimentally & theoretically during many years the good effects of crossing & the evil effect of close interbreeding; & the difference in vigour, & size & power [illeg] & health of the offspr[ing] in the 2 cases is in most cases extraordinary.— In Chap 17 of my work on the variation of Domestic Anim I have given a resume of my results,—² & these might be consulted by any one who wishes to see what is at present [known] on the subject. In various European countries & the U. States the most contradictory opinions owing to the [continued] want of any reliable data have been found. whether the marriage of near relatives is in any way injurious to man..³

Some time ago I went to the of the Registrar general, suggesting that during the next Census, a return should be demanded, whether in each family the parents were related in blood;⁴ for it w^d then it w^d be possible by comparing the average numbers of the [surviving] children, of related & not related parents, to judge of the vitality of the children in the 2 cases, or of the fertility of the parents.

I have every cause to believe that the time will soon come, when this subject will be [emerging] as highly important for the welfare of mankind, though at present the subject has [8 words illeg].