2. It also becomes a factor of importance in indirectly producing disease of the nervous system, through hereditary influence. As we have so frequently had occasion to observe hitherto, any abnormal condition which has existed sufficiently long to become a true diathesis, not only may, but is very likely to be transmitted in some form or other to those who come after. This has been shown in relation to the influence of over-stimulation from application to study, and from the effects of alcohol; and though the effects of both these are essentially different from that of tobacco, yet we can but consider the latter as very injurious in its influence. Indeed, I am inclined to regard the physiological effects of tobacco when used to excess as likely to appear in offspring in the form of a lower grade of intellectual and moral character, though to a less extent than are those of alcohol. CHAPTER XII. SEX IN RELATION TO INSANITY. The relative frequency of insanity in the sexes varies somewhat in different countries and under the differing conditions of civilization. There can be no doubt that under circumstances and surroundings adapted equally to the maintenance of the health of both sexes, there would be as little disease of brain in the one as in the other. The conditions of life, however, nowhere exist bearing alike on both. While there are certain hardships, exposures, and dangers to be endured by the male to which the female is little liable, on the other hand there are many unfavoring experiences growing out of the nature of her labor and duties as arranged in modern civilization, as well as from the constitution of her system, from which the male sex is exempt. While the male is more often exposed to the inclemency of weather, the cold of winter and the heat of summer; while he must endure the hardships of war by sea and land, and the larger expenditure of physical force in the performance of his labor; while he is much more liable to injury of the nervous system from accidents arising in connection with his exposures in the larger sphere of locomotion; on the other hand the female is much less favorably situated in relation to the beneficial effects arising from living much in the open air. The sphere of her activities is much more circumscribed, and the larger portion of her time is passed in-doors, and often in an atmosphere less favorable as to its hygienic conditions. There are, however, certain physical conditions of the female sex which are intimately connected with the sexual system, and which have been supposed, by both lay and professional persons, to be closely allied, as causes, to mental derangements, to which I desire to call attention for the present. These will relate more especially to the unmarried.