190 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



not all the. cases in which we would anticipate that intermarriage might be productive of deaf oft- 

 spring. The late Dr. Harvey L. Peet states, as the result of his researches,* that the hearing 

 brothers and sisters of a deaf-mute are about as liable to have deaf children as the deaf-mute himself. 

 It is only reasonable to assume that a tendency towards deafness exists in a family containing 

 more than one deaf-mute, so that if hearing persons belonging to such families were to intermarry, 

 or were to marry deaf-mutes — or if a consanguineous marriage were to take place in such a family — 

 we would not be surprised if souic of the ofi'spriug should be deaf. In addition therefore to the 

 20,474 deaf-mutes referred to above, ice mvst include the hearing and speaMng members of their families 

 before ice can form an adequate conception of the number of persons who possess a predisposition towards 

 deafness. 



It will thus be seen that we have abundant materials in the United States for the formation 

 of a deaf variety of the human race by selection in marriage. 



*Araerican Annals of the Deafand Dumb, Vol. VI, p. 235. 



