CAN MAN BE MODIFIED BY SELECTION? 21 



per cent, may have been between deaf persons, but even this is an 

 alarming frequency, if it is true that the children of such unions are 

 predisposed to deafness. 



If it is true that our system of educating the deaf is responsible 

 for the number of marriages between deaf persons, we should expect 

 to find these marriages increasing in numbers, and Professor Bell has 

 compiled from the table above quoted the following table, which 

 shows that this is the case : 



These two tables show that the tendency of deaf-mutes to select 

 deaf-mutes as their partners in marriage is very pronounced, and that it 

 is much more developed now than it was during the early half of the 

 century, and that it is steadily increasing. 



Thus there is every indication that this process of selection will go 

 on from generation to generation, and that a large proportion of the 

 deaf children of deaf parents will themselves marry, and that, of those 

 who marry, the majority will marry deaf-mutes. 



If it is true that deafness is hereditary, this can have only one re- 

 sult the increase of deafness. 



There are very few reliable statistics regarding the number of chil- 

 dren born to deaf-mutes, or the proportion of deaf children, but Dr. 

 Turner, formerly the Principal of the American Asylum, stated, in 1868, 

 that statistics carefully collated from records kept of deaf-mutes, as they 

 have met in conventions at Hartford, show that in eighty-six families, 

 with one parent a congenital deaf-mute, one tenth of the children were 

 deaf; and in twenty-four families, with both parents congenital deaf- 

 mutes, about one third were bom deaf. 



In 1854 Dr. Peet, the Principal of the New York Institution, said 

 that, of all the families of which he had records, " about one in twenty 

 have deaf-mute children ichere both parents are deaf-mutes, and about 

 one in one hundred and thirty-five ichere only one is a deaf-mute ; 

 and that the brother and sister of a deaf-mute are about as liable to 

 have deaf-mute children as the deaf-mute himself, supposing each to 

 marry into families that have, or each into families that have not, 

 shown a predisposition toward deaf-dumbness" 



Our author has attempted to trace out from the scanty records the 

 history of certain families in which deafness is hereditary, and he has 

 expressed the facts in a number of graphic diagrams, two of which are 

 here reproduced. 



