With regard to consanguineous marriages and their effect on deafness we are on surer ground, so far as may be indicated by statistical data. This question is found in very great measure to be connected with that of deaf relatives in general. The matter appears to be largely a part of a law of wide application, namely, that in the blood relationship of parents the possibilities are intensified of the perpetuation of a certain strain, which holds true no less with the transmission of deafness. Consanguineous marriages are perhaps not of sufficiently frequent occurrence, so far as concerns the effect on deafness, to require special action; but in the consideration of such marriages in general, their part in the causation of deafness should have due weight; and whatever may be said regarding them in other relations, they are to be avoided if we wish to remove all chances of this kind of deafness resulting. The problem of deaf relatives and their connection with congenital deafness is a very large one. Attention however, has mostly been focused upon it in relation to the intermarriage of the deaf and its effect upon their offspring. Indeed, in such unions there has already been more or less concern, and there has even been question whether it is a wise or unwise policy to allow the deaf to marry other deaf persons. The deaf, as we shall discover, not only find their companions for social intercourse among similar deaf persons, but _a fortiori_ very often seek such persons for their partners in marriage--in fact, more often than they do hearing partners, nearly three-fourths of the married deaf being married to deaf partners.[56] Not only has it been feared that the offspring of such marriages might likewise be deaf, but there has also been apprehension lest in their encouragement there might result a deaf species of the race.[57] From our discussion, however, we have found that in most of the marriages of the deaf we have but small reason for disquiet. If deafness in the parent is really adventitious, there is little possibility of its passing on to the offspring. When the deafness in the parent is itself congenital, the situation becomes more serious. If in such case there is no added risk from the existence of deaf relatives, the likelihood of transmitting deafness need not always be a matter of deep concern, though the hazard is materially larger than for adventitious deafness. When there are deaf relatives involved, the peril, made stronger if coupled with congenital deafness, is most pronounced; and, indeed, the existence of collateral deafness seems a more certain sign of warning than direct heredity itself. Finally, even in the marriage of the deaf with the hearing, the dangers are not in fact lessened if conditions otherwise unchanged are attendant.