The cerebral defect once established, the modes in which it may be manifested in subsequent generations present no uniformity whatever. Insanity in a parent may be followed by any possible form of mental irregularity in the descendant,--insanity, idiocy, epilepsy, drunkenness, criminal impulses, eccentricity. And so, too, eccentricity, even of the least prominent kind, may be followed by grosser eccentricity, or even overt insanity, in the descendant. The cerebral defect is not necessarily manifested in an uninterrupted series of generations, for it often skips over one, and appears with redoubled energy in the next; and thus, in looking for proof of hereditary disease or defect, we are not to stop at the next preceding generation. We are too little acquainted with the laws of hereditary transmission to explain these things. We know this, however, that, side by side with that law which decrees the transmission of defects as well as excellences, there exists another law which restrains deviations from the normal type, which extinguishes the errant traits, and reestablishes the primitive characters of the organism. The combined and alternate action of these two laws may produce some of the inscrutable phenomena of hereditary transmission. The transmission of the cerebral defect is often manifested in a manner exceedingly embarrassing to all who hold to the prevalent notions respecting sanity and insanity. It is sometimes confined to a very circumscribed range, beyond which the mind presents no material impairment. The sound and the unsound coexist, not in a state of fusion, but side by side, each independent of the other, and both derived from a common source. And the fact is no more anomalous than that often witnessed, of some striking feature of one parent associated in the child with one equally striking of the other. It is not the case exactly of partial insanity, or any mental defect, super-induced upon a mind otherwise sound,--for such defect is, in some degree, an accident, and may disappear; but here is a congenital conjunction of sanity and insanity, which no medical or moral appliances will ever remove. These persons may get on very well in their allotted part, and even achieve distinction, while the insane element is often cropping out in the shape of extravagances or irregularities in thought or action, which, according to the stand-point they are viewed from, are regarded either as gross eccentricity, or undisciplined powers, or downright insanity. For every manifestation of this kind they may show no lack of plausible reasons, calculated to mislead the superficial observer; but still the fact remains, that these traits, which are never witnessed in persons of well-balanced minds, are a part of their habitual character. When people of this description possess a high order of intellectual endowments, the unhealthy element seems to impart force and piquancy to their mental