28 THE CAVENDISH LECTURE 



the suffering denoted by these percentages, not only on the indi- 

 viduals themselves, but on their friends and relatives, and what is 

 more important, on the nation as a whole? I believe, if the 

 general public, but above all the medical profession, once fully 

 realised the very large part which heredity plays, not only in cases 

 of deformity, but in cases of general mental and physical debility, 

 where it leads to many forms of degeneracy, they would be most 

 wholly and heartily with me when I say that only a very thorough 

 eugenic policy can possibly save our race from the evils which 

 must flow from the antagonism between natural selection and 

 medical progress. You will say : " In what way can help be most 

 efficiently given to such a eugenic policy ? '"' There are two ways 

 in which it can be done — by public action and by personal 

 influence. 



By public action : In suppcjrting some measure, whether it be 

 the present Government Bill or a modified form of it, for the 

 segregation of the mentally defective. By insisting in and out of 

 season on the necessity for a general register of the insane, so that 

 there may be really definite information as to the insane popula- 

 tion of this country. By forwarding every movement for the 

 notification and registration of all diseases and deformities of 

 which we have already definite knowledge as to their hereditary 

 character, /. e. haemophilia, epilepsy, albinism, congenital cataract, 

 deaf-mutism, etc., and of all diseases, non-hereditary in character, 

 where an active condition is injurious to offspring. 



But great as is the influence of medical opinion on public action, 

 it is more than equalled by the weight which the individual medical 

 man can exert in his private relationship either as consultant or as 

 family doctor. He is the confidential friend of many men and 

 women, and as such in a quiet and unobtrusive way he can do 

 much to encourage the fit to parentage and discourage the 

 unfit. The public is in a receptive mood at the present time - I 

 feel sure of this by the number of letters of inquiry, often with 

 elaborate pedigrees, which reach my laboratory — and a very 

 little directive from medical advisers may have great ultimate 

 national value. 



Be this as it may, I am certain there is from the racial stand- 

 point a divergence between the conception of natural selec- 

 tion and the progress of medical science; I see only one way of 

 bringing the two into harmony. If we suspend — as we all agree 

 we ought to suspend — the stiingenl selection of the living, then 



