Passing now to the psychological traits and characters, we observe that the same law pertains. The heredity of mental qualities is quite as persistent as that of the physical; imagination, memory, will, intellect, the sentiments and passions, may all be inherited. It is estimated that not less than forty per cent. of eminent poets have had illustrious relatives. The families of Darwin, Cuvier, Bacon, Sir Benjamin Brodie, John Adams, Lord Macaulay, Madame de Staël, present good illustrations of the inheritance of intellectual ability. But no less surely are the characteristics of _morbid_ mental activity transmitted from one generation to another. The records of asylums all indicate that the tendency to insanity, in some of its forms, is one of those most likely to be inherited. It is thought that more than one half of the admissions to English asylums present evidence of an inherited taint. The same is probably true in reference to admissions to asylums in the United States, though it is exceedingly difficult to arrive at the truth in all cases, inasmuch as many persons are inclined to deny that any such tendency exists in their families, lest such a fact should appear to its prejudice in some way or other. It is not the case, however, that definite forms of insanity always repeat themselves, but, on the contrary, change, so that a case of mania may appear in the second generation as a case of melancholia, or acute dementia; and, _vice versa_, melancholia may appear as dementia. Information concerning the inheritance of general paralysis is not so definite; indeed, this form of insanity generally manifests itself in those having no tendency by inheritance, and would seem to be more frequent among the strong and robust, and also has a tendency to appear in the very prime of life. It is not necessary that the tendency toward unstable mental action should be fully developed in the parent in order that it may so appear in the child. Parents who have for years been very odd or singular in their habits of life and manner of speech and mental operations; those who are subject to periods of depression, and are accustomed to look upon the dark side of daily experiences; mothers, more often, perhaps, who have all their lives been "nervous" or irritable and easily excited, impress more or less profoundly these abnormal conditions upon their offspring. Great singularity of conduct habitually displayed, periods of depression, irritableness, and nervousness, when crossed with similar characteristics in the other parent, or other unusual ones, not infrequently develop into actual insanity in succeeding generations.