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one of those ailments which nature entails as a hereditary 

 reminder of parental imperfection is well known, and in it 

 frequently we have a good exemplification of the law of 

 atavism ; the defect appears to skip one generation and to 

 re-appear in the next. I have just at present a lady under 

 my care who is very deaf, and whose mind is beginning to 

 fail j she is one of a family two other members of which 

 are deaf. Deafness has been transmitted for generations, 

 and, coincident with the deafness, there is also a family 

 history of insanity. 



Occasionally, though we cannot find evidence of deafness 

 in the parents, curiously enough two or three brothers or 

 sisters are affected. The deafness at other times will be 

 found on the father's or mother's side, while the parents 

 have escaped. Such hereditary deafness is nearly always of 

 a most unfavourable type, and treatment generally ends in 

 a negative result. In a great many cases the physician does 

 not see the patient until the deafness is far advanced and 

 there is evidence of serious middle and internal ear trouble. 

 . . . It is a fact, and a most vital one in regard to this 

 form of deafness, that we frequently find it first make its 

 appearance after puberty, or even later on." Thus, hearing, 

 of every form and variety, whether of the nature of anaes- 

 thesia or hypersesthesia, may have an element of heredity in 

 its production, which may have become decreased, inten- 

 sified, or otherwise modified, in its descent from one 

 generation to another. 



With regard to heritable peculiarities of touch, I have 

 already referred to them when discussing the heredity of the 

 sensorial qualities. There can be no doubt that parents 

 transmit to their children the most singular perfections and 

 imperfections of touch ; and all these tactile sensations, as 



o 



