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SCIENCE. 



[Vol. XVII. No. 418 



SCIENCE; 



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HEREDITARY DEAFNESS. — A STUDY. 



The American Asylum is the oldest school for deaf-mutes 

 in the United States. Its history covers three-quarters of a 

 century. It has had under instruction, including those now 

 in school, 2,459 pupils, a number exceeded by that of but 

 one other school in this country. There have been nearly 

 six hundred marriages, in which one or both of those mak- 

 ing the marriage contract were once pupils in the school, 

 and the offspring of these marriages number over eight hun- 

 dred children. The records of the school have been care- 

 fully preserved, and from these and much personal inquiry 

 we have been able to gather some facts which will be inter- 

 esting at this time, when the question of hereditary deafness 

 is receiving so much public attention. It will be seen at 

 a glance that the field is a favorable one for the study of 

 this subject, and, though not broad enough to warrant the 

 drawing of general conclusions therefrom, the facts are valu- 

 able pointers, and may serve as one of the studies, which, 

 when collated, will give sufficient data to work out a general 

 law. 



That there is a tendency to deafness in the offspring of 

 congenitally deaf parents, there can be no doubt. Nor can 

 it be doubted that this tendency is comparatively slight in 

 the offspring of parents both of whom are adventitiously 

 deaf. But let the facts speak for themselveg. They are be- 

 lieved to be reliable so far as they go; but it is quite proba- 

 ble that in some of the families included in the following 

 table other children may have been born since the dates at 

 which the facts were reported. The general proportion, 

 however, in all probability, would not be affected by such 

 additions. In this table, c. ^congenitally deaf; ad. = ad- 

 ventitiously deaf ; h.== hearing; u. ^ age at which deafness 

 occurred unknown. 



When we consider how heavy a handicap congenital deaf- 

 ness is, it is appalling to think that 31 per cent of the off- 

 spring of the congenitally deaf may be born deaf. But I 

 believe that this proportion is far above that of the general 



average of such cases throughout the country. I believe 

 that there are causes at work in New England, not in oper- 

 ation to any thing like the same extent in other parts of the 

 country, which will account for no inconsiderable part of 

 the large percentage of congenital deafness in the offspring 

 of congenitally deaf parents in that section. 



Facts gathered from the Records of the American Asylum at 

 Hartford, Conn. 



' Three families are reported with several hearing children in each. 



Of the fifty-two families in which both parents are con- 

 genitally deaf, twenty-three have congenitally deaf children. 



Of the thirty-seven families in which the husbands are 

 congenitally deaf and the wives adventitiously deaf, two 

 have deaf children, — four in^ one family, and one in the 

 other. 



Of the fifty-one families in which the fathers were adven- 

 titiously deaf and the mothers congenitally deaf, seven pro- 

 duced deaf children, and nine of the congenitally deaf chil- 

 dren come from two families. 



There are fifty-five families in which both parents are 

 adventitiously deaf, and from these have sprung four con- 

 genitally deaf children, — one in each of four families. 



Four of the sixteen families in which the husbands hear 

 and the wives are congenitally deaf have deaf children. 



In five families out of ttie twenty-six in which the hus- 

 bands are congenitally deaf and the wives hear, there are 

 children born deaf. 



Six of the twenty-seven families in which the husbands 

 were congenitally deaf and the state of the hearing of the 

 wives is unknown produced congenitally deaf children. 



Of the twenty-six families in which both parents are deaf 

 and have congenitally deaf children, there are five families, 

 in which one of the parents has one deaf parent, seventeen 

 families in which both parents have deaf relatives of the 

 same generation, four in which one parent has deaf relatives 



