Licence: Public Domain Mark
Credit: Deaf-mutism / by Holger Mygind. Source: Wellcome Collection.
Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.
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![resulting from congenital pathological changes of the organs of hearing, and that resulting from such changes which are acquired after birth ; v. Troltsch sub-divides the latter into earher and later-acquired deaf-mutism. The former is exhibited in children who have never acquired speech, but who have heard; the latter appears in children after they have learnt to speak [141, p. 5i8]. It is my intention in the present work to adhere, as far as possible, to the division of deaf-mutism into that caused by congenital deafness and that resulting from acquired deafness. I have endeavoured, so far as I have been able, to show how far these two forms differ from each other in etiology, morbid anatomy, and symptomatology. AUhough, theoretically, this classification is easily carried out, it is often difficult to distinguish between deaf-mutism resulting from foetal changes, and that caused by deafness acquired in infancy. In a great number of cases, however, it is easy to determine the origin of deaf-mutism, since numerous investigations, in which the deaf-mutes examined have been divided into these two classes, prove with certainty that each class has its pecu- harities, of which a detailed account will be given. RELATIVE PROPORTION OF CONGENI- TAL TO ACQUIRED DEAFNESS.—Literature contains numerous statements as to the numerical comparison between deaf-mutes with congenital and those with acquired deafness. E. Schmalz collected a number of statistics which had appeared before the publication of his work [70, p. 6], and came to the conclusion that there were about double as many](https://iiif.wellcomecollection.org/image/b21709968_0023.jp2/full/800%2C/0/default.jpg)
