MARKIAGE AMONG DEAF-MUTES. 



123 



It is obvious that persons born deaf run considerable risk of 

 having deaf offspring if they marry persons who are also born deaf. 



If we take all the marriages of congenitally deaf persons, without 

 reference to whether they married deaf or hearing persons, we have 

 five independent sets of statistics from which we may derive infor- 

 mation regarding the effects upon the offspring. ( 1 ) My own 

 researches indicate that where one or both of the parties were born 

 deaf there will be fifteen deaf children in every hundred families ; 

 Dr. Gillett's statistics give eighteen deaf children to every hundred 

 families ; (3) Dr. Turner's, thirty-two ; (4) Mr. Williams's, forty- 

 seven ; and (5) Mr. Connor's, ninety- five. 



Table II. — Concerning the Offspring of Couples One or Both of Whom 



were born Deaf. 



Authority. 



Total 

 Number 



of 

 Families. 



Total 

 Number of 



Deaf 

 Children. 



Percentage. 

 Number of 

 Deaf Chil- 

 dren to 

 every 100 

 Families. 



Turner (1868) ... 

 Bell (1883) 

 Connor (1888) ... 

 Gillett (1891) ... 

 Williams (1891) 



190 



360 



22 



71 

 211 



61 

 56 

 21 

 13 

 101 



32-1 

 15-5 

 9V4 



18-3 



17-8 



Persons who are reported deaf from birth, as a class, exhibit 

 a tendency to transmit the defect ; and yet when we come to 

 individual cases we cannot decide with absolute certainty that any 

 one was born deaf. Some who are reported deaf from birth probably 

 lost hearing in infancy; others reported deaf in infancy were probably 

 born deaf. For educational purposes the distinction may be im- 

 material, but in the study of inheritance it makes all the difference 

 in the world whether the deafness occurred before or after birth. 

 Now, in my researches I flunk I have found a surer and more safe 

 guide to those cases that are liable to transmit the defect. 



The new guide that I would give you is this : look at the family 

 rather than at the individual. You will find in certain families that 

 one child is deaf and all the rest hearing, the ancestors and other 

 relatives also being free from deafness. This is what is known as a 

 " sporadic " case of deafness, — deafness which afflicts one only in a 

 family. 



Well, the deafness in such cases may be accidental. There is no 

 proof that such deafness is liable to be inherited, excepting where the 

 person is reported deaf from birth. In the vast majority of cases 

 reported deaf from birth there is an undoubted tendency to inheri- 

 tance; but where the deafness is caused by meningitis, scarlet-fever, 

 or like causes, and no other case of deafness exists in the family, 

 there is probably little, if any, tendency to inheritance. But when 

 you have two members of your family deaf, or three, or four, or five, 

 there you have the proof that a tendency to dtalness exists in the 

 family. What I term " family deafness " exists there. Something 

 has been transmitted from the parents to the children that has 



