There are, besides the above men tioned, several other remote causes, which are, more or less properly, sup posed to play a part in the etiology of deaf-mutism; of these the most impor tant are the following:— A lcoholism in the Parents.—Although the abuse of alcohol is extremely com mon, and although. we have no informs, tion as to its frequency, on the whole; I still, several reports seem to indicate that I alcoholism in the parents plays some part in the etiology of deaf-mutism. Among the most important facts as to this ques tion must be mentioned those stated by Uchermann in Norway, where, in eases of deaf-mutism of non-hereditary origin, alcoholism was found with double fre quency among the parents of the deaf mutes with congenital deafness than among parents of deaf-mutes with ac quired deafness. It is at present im possible to form any accurate opinion as to whether alcoholism makes itself felt by weakening the parents' constitution, or whether it is an expression of a nerv ous disposition.
Syphilis in the Parents.—This disease has, on the whole, been found compara tively seldom among the parents of deaf mutes. This does not, however, prove that syphilis plays no part in the etiology of deaf-mutism, for it is often difficult to discover, by questioning, whether a person has, or has not had, this disease, and it is also possible that investigations have, up to the present, been deficient in this particular. It is, at all events, cer
tain that syphilis in the parents may produce a form of deafness in the chil dren, appearing in the later years of childhood, and often leading to deaf mutism. This form of deafness will be mentioned more particularly under the special etiology of acquired deaf-mutism.
Age and Difference in Age of Parents.
—Meniere was the first to draw atten tion to these two factors in the origin of deaf-mutism, stating that, according to his experience, deaf-mutes were often the children of young parents, and that such marriages were frequently sterile or re sulted in weakly offsprings. Later inves tigations have, however, not confirmed this.
Fertility of Marriages.—All authors who have.directed their attention to this subject agree that marriages producing deaf-mutes are remarkable for their fer tility. According to Uchermann, this may be explained by supposing that, the greater number of children there are born, the more strongly the hereditary disposition to deaf-mutism, hmmophilia, etc., shows itself.