Page:Popular Science Monthly Volume 48.djvu/692

620, and there is ample evidence that the value in breeding of a given parental characteristic does depend upon its origin, and that one due to nurture has a very different value from one which is itself inherited.

Of the 2,459 deaf pupils of the American Asylum, nearly six hundred have married and have become the parents of over eight hundred children, of whom 104, or more than twelve per cent, were born deaf—a ratio which is great enough to prove that inheritance has some influence. Analysis of the records shows clearly, however, that these deaf children are not uniformly distributed among the married pupils of the asylum, but that the result is influenced by the character of the parental deafness. From 283 of the 590 marriages no children are reported, while from three other families no report is made except that all the children hear, so that the 811 child en which are reported are from only 304 families, and in many of them only one parent was deaf. Of the 101 children of forty of these marriages none are reported as deaf, and all but eleven are reported as hearing, and the 710 children are from the remaining 264 marriages. In fifty-two of the marriages both father and mother were congenitally deaf, and these are the parents of forty-eight out of the 104 congenitally deaf children, but they are the parents of only 151 of the total number of 811 children, and nearly thirty-two per cent of all the children of these congenitally deaf parents are congenitally deaf.

In two of the groups in which the marriages may be classified the number of marriages and the number of children are about equal, but there is a most remarkable difference in the number of deaf children.

In fifty-five marriages, with 139 children, both parents are reported as adventitiously deaf, while in fifty-two marriages, with 151 children, both were congenitally deaf. In the latter group fifty-two children, or 31·78 per cent, are congenitally deaf, only eighty-eight are stated to hear, and no facts are given about the hearing of fifteen of them. In the first group only four of the 139 children, or 3·87 per cent, are reported as congenitally deaf, 129 are reported as hearing, and six are not reported.

I have divided all the marriages into four groups: In one all the children hear; in the second from five to six per cent are deaf; in the third from twelve to eighteen per cent are deaf; and in the fourth 31·78 per cent are deaf. In the first group, in which all the children hear, five of the marriages, with eighteen children, are between a hearing husband and a wife who is adventitiously deaf; one marriage with four children between a hearing man and a woman the source of whose deafness is unknown; six marriages, with thirteen children, where the wife hears and the husband is adventitiously deaf; twenty-three marriages, with