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PHYSICAL HEREDITY 20 



father was vigorous at nearly seventy. M. Es- 

 quirol says that one-half the cases of insanity 

 amongst the higher classes in France, and about 

 one-third amongst the lower classes, have been 

 inherited from parents or ancestors. According 

 to one authority, seventy-seven per cent, of the 

 cases at the Bicetre were hereditary, and, accord- 

 ing to Dr. Burrows, eighty-four per cent. Two 

 important considerations in regard to this ques- 

 tion should be given full weight : first, that the 

 native inferiority or taint may be of very differ- 

 ent degrees of intensity, so as, on the one hand, 

 to conspire only with certain more or less power- 

 ful exciting causes, or, on the other hand, to give 

 rise to insanity even amongst the most favourable 

 external circumstances. Second, that not only 

 insanity in the parents, but any form of nervous 

 disease in them — epilepsy, hysteria, and even 

 neuralgia — may predispose to insanity in the 

 offspring ; as, conversely, insanity in a parent 

 may predispose to other kinds of nervous diseases 

 in the offspring.^ What is true of consumption 

 and insanity is true of all nervous diseases, of 

 gout, dyspepsia, skin diseases, and so on through 

 the list. 



^ Physiology and Pathology of the Mind, Second Edition, London, 

 P- 243. 



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