It is now impossible to deny the heredity of mental troubles, as well of those in the case of which we do not know the accompanying anatomical lesions as of those with which we think we are better acquainted, as in general paralysis and senile dementia. Still less doubtful is it that our cases are most frequently not of direct and identical heredity, but usually of what we call collateral and dissimilar heredity. The son may not inherit from his father, and if the nephew inherits, he will generally seem to be afflicted with a different mental affection from that of his uncle. It must, therefore, be understood that what is meant by heredity in mental diseases does not necessarily correspond with the definition of normal biological heredity.
This frequent dissimilarity in the inheritance of madness becomes more clearly denned when we regard the alliances of the psychopathic family. Nervous troubles very different in their manifestations are frequently met with in families of insane. Prichard has given the name of moral insanity to a mental trouble which prompts to abnormal or mischievous acts while consciousness of their moral nature is wanting. This kind of insanity differs from the impulsive insanity, in which the patient is urged to violent, harmful, or criminal acts by a force which, though invincible, leaves him able to appreciate more or less sanely the character of those acts.
Vice and crime are, furthermore, often hereditary, like insanity. More frequently they are met in families combined with the most various mental disorders—insanity, imbecility, idiocy, etc. The combination of insanity and crime is observed not only in the same family, but often, too, in the same person. Physicians of penitentiaries have long insisted on the frequency of mental disorders among the convicts, and have become convinced that the causes of what is called prison-madness are inherent in the prisoners and not in the prison. It has, moreover, been remarked that debauchery and instinctive perversions are often met with in the hereditary antecedents of insane persons.
Not criminality only has family connections with insanity, but the artistic temperament and genius are frequently associated with it. An old writer has said that there never was a great genius who had not some tinge of insanity. Numerous men, illustrious under different titles, have been attacked with various mental troubles, or have belonged to families in which such troubles were common. The frequency of such associations suggested to Moreau de Tours his saying that genius is a nervous disorder. Further, while great men are rarely exempt from a trace of folly, madmen have no less frequently had a share of genius. Thus we sometimes find in the asylums calculators and musicians of remarkable aptitude in their respective lines. M. H. Nordau (De-
