47 



progenitors. By the term heredity we understand the 

 transmission of organic dispositions from parents to children. 

 Mad doctors have, perhaps, more frequent occasion than 

 others for observing this hereditary transmission, as also 

 the various transformations which are exhibited in the 

 descendants. They are aware that a simple neuropathic 

 state of the parents may produce in the children an organic 

 disposition which will result in mania or melancholy 

 nervous affections which, in turn, may give rise to more 

 serious degeneracy, and terminate in the idiocy or imbecility 

 of those who form the last links in the chain of hereditary 

 transmission." 



But to return. Deaf-muteness of the parents may be so 

 metamorphosed in their children as to result in a minimum 

 of hearing, imperfectly-articulate speech, mental dulness and 

 weakness, or even idiocy. Many instances of these facts 

 are given by Menckel, the celebrated anatomist. The main 

 fact, however, which we have to bear in mind, is that all the 

 phenomena of hearing, whether of the nature of hyper- 

 assthetic or peculiarly acute, or of anaesthetic, or that 

 amounting almost to deafness with every intermediate 

 grade are undoubtedly heritable and transmissible in the 

 sense which I have explained. Like all other laws, heredity 

 has its exceptions : thus the comparative infrequency of the 

 inheritance of deaf-mutism. How these transformations or 

 metamorphoses occur is beyond the power of science to 

 say. With regard to deaf-mutism, probably Sedgwick, as is 

 mentioned before, is right in supposing that the prepotency 

 of the same characteristics in both parents, in some 

 mysterious way, neutralises the hereditary element so that 

 they are not transmitted ; but, be this as it may, heredity is 

 a law which is always being realised, but never ideally so ; 



