NERVOUS DISEASES . 279 



animals namely, the opponens muscles of the hand." (4) Hamil- 

 ton suggests, inter alia (1900, p. 298), that the "germ-track 

 followed in the ontogeny of the nerve-cells is very short, far 

 shorter than in the case of many other cells throughout the 

 body, and hence a state of maturity is reached at a comparatively 

 early period, with an inclination to premature decay." (5) It 

 may also be noted that, especially as regards his nervous system, 

 the so-called civilised man takes liberties of unnatural function 

 and unnatural environment, which often tax the plasticity of 

 protoplasm beyond the limits of endurance, marvellously wide 

 as these are, and allow inborn weaknesses to find dire expression. 

 For these and other reasons, then, the nervous system of man 

 is peculiarly liable to disease. 



Weaknesses, abnormal peculiarities, and actual diseases of 

 the nervous system are not only very common, but they appear 

 to be peculiarly persistent in family histories. In old days 

 it was often remarked that generation after generation of a 

 particular family might be " possessed of the devil " ; and 

 there were families of " sorcerers " and " witches " who turned 

 their hereditary neuroses to account. So now we speak of the 

 neuropathic family. 



It is generally admitted that lack of control, morbid idiosyn- 

 crasies, subjection to delusions, monomania, hysteria, epilepsy, 

 chorea, locomotor ataxy, extreme passionateness, homicidal 

 and suicidal mania, insanity and imbecility, tend to reappear 

 generation after generation with appalling regularity. It is 

 often said that about one-fourth of those who are confined in 

 lunatic asylums have had some more or less insane not-remote 

 ancestor. 



In regard to this very difficult question we wish simply to.. 

 make three remarks : (i) in many cases what the facts suggest 

 is the inheritance of a general, not a specific, predisposition ; 

 (2) on the other hand, there are some instances of apparently 

 very precise and specific inheritance, as if some very definite 



