October 5, 1900.] 



science: 



525 



relatives is just as likely to result in deaf chil- 

 dren as a marriage of. the deaf. 



The report will be welcomed by all students 

 of inheritance from the scientific standpoint ; 

 although it was undertaken and has been carried 

 on, we are told, "in the hope that it might be 

 of service to the deaf, and to society by settling 

 definitely the question whether or not the deaf 

 are more liable than hearing persons to have deaf 

 children ; and if it should appear that, notwith- 

 standing the numerous instances to the contrary, 

 thej' are more liable to this result, by ascer- 

 taining whether or not the liability is increased 

 by the marriage of the deaf with one another ; 

 also whether certain classes of the deaf, how- 

 ever married, are more liable than others to 

 have deaf children ; and, if this should prove 

 to be the case, by determining how these classes 

 are respectively composed, so that as a result 

 of the conclusions reached, in many instances 

 deaf persons might be advised to follow the 

 choice of their own hearts in marriage, with no 

 restrictions whatever, except such as should 

 influence all right-minded persons in this im- 

 portant matter ; while in cases where the deaf- 

 ness of the parent was unquestionably more 

 liable than in others to reappear in the off- 

 spring, the persons interested might be effect- 

 ively warned in time of the danger in- 

 curred." 



The tables of facts regarding the deaf which 

 make up most of the report are accompanied by 

 a thorough and exhaustive analysis, which 

 shows that this practical philanthropic purpose 

 has been accomplished, and that Professor Fay 

 is now able to give to those deaf persons who 

 contemplate marriage advice which has the 

 value of scientific demonstration. 



Professor Bell has shown that marriages of 

 the deaf are more common in America than in 

 Europe, that they have increased at a higher 

 rate of progression during the present century, 

 that the probability of deaf children is much 

 greater among the deaf than in the community 

 at large, and that deafness — not mere hardness 

 of ^ hearing, but what is called ' deaf dumb- 

 ness ' — is also increasing among us, and that 

 we are threatened with a deaf variety of the 

 human race. At the same time, it is clear that 

 the probability of deaf children is not equally 



great among all deaf persons who marry and 

 have children. A person who has lost hearing 

 bj"^ accident or disease, at however early an age, 

 may possibly be in no more danger of trans- 

 mitting the peculiarity than one who has lost 

 an eye or an arm. It is therefore highly impor- 

 tant, in the interest of the deaf as well as in the 

 interest of the community, to determine the 

 conditions which are favorable and those which 

 are unfavorable to the hereditary transmission 

 of deafness. 



This report contains more than three hundred 

 and fifty pages of statistical information, giving, 

 for some 8,000 deaf persons who have married, 

 data regarding the origin of their deafness, the 

 hearing or deafness of the partner in marriage, 

 the date of marriage, the number of children, 

 the number of deaf children, a record as to the 

 hearing or deafness of brothers and sisters, and 

 information as to the existence of other deaf 

 relatives. These tables, which contain a record 

 of the marriages of the deaf far larger than all 

 previous records put together, are of great 

 interest to all students of inheritance, but their 

 motive is philanthropic rather than scientific. 



While deaf persons are much more likely to 

 have hearing children than to have deaf chil- 

 dren, they are much more likely than ordinary 

 normal-hearing persons to have deaf children. 

 Less than one-tenth of one per cent, of all the 

 children of normal parents are deaf, but if one 

 or both parents are deaf, nearly nine per cent, 

 of all the children are deaf. In other words, a 

 normal-hearing pair have no reason to fear that 

 a deaf child will be born to them unless they 

 have more than a thousand children ; while if 

 one parent or both are deaf, and they have 

 eleven children, they may, on the average, ex- 

 pect to have one deaf child. 



The probability of deaf children is not, how- 

 ever, equally great for all deaf persons, since it 

 depends upon the character of the parental 

 deafness. Marriages of the congenitally deaf, 

 that is, of persons who have never, at any time 

 in their lives, shown evidence of hearing, are 

 far more likely to result in deaf offspring than 

 marriages of the adventitiously deaf, that is, of 

 those who have once heard and have sub- 

 sequently lost their hearing. Of 526 marriages 

 between a congenitally deaf person and a con- 



