Among most modern nations, the civil laws fixing the earliest date of marriage seem to have been made without any reference to physiology, or with the mistaken notion that puberty and nubility are identical. It is interesting to note the different ages established by different nations for the entrance of the married state. The degenerating Romans fixed the ages of legal marriage at thirteen for females, and fifteen for males. The Grecian legislator, Lycurgus, placed the ages at seventeen for the female, and thirty-seven for the male. Plato fixed the ages at twenty and thirty years. In Prussia, the respective ages are fifteen and nineteen; in Austria, sixteen and twenty; in France, sixteen and eighteen, respectively. Says Mayer, "In general, it may be established that the normal epoch for marriage is the twentieth year for women, and the twenty-fourth for men." Application of the Law of Heredity.--A moment's consideration of the physiology of heredity will disclose a sufficient reason why marriage should be deferred until the development of the body is wholly complete. The matrimonial relation implies reproduction. Reproduction is effected through the union of the ovum with the zoosperm. These elements, as we have already seen, are complete representatives of the individuals producing them, being composed--as supposed--of minute gemmules which are destined to be developed into cells and organs in the new being, each preserving its resemblance to the cell within the parent which produced it. The perfection of the new being, then, must be largely dependent on the integrity and perfection of the sexual elements. If the body is still incomplete, the reproductive elements must also be incomplete; and, in consequence, the progeny must be equally immature. Early Marriage.--The preceding paragraph contains a sufficient reason for condemning early marriage; that is, marriage before the ages mentioned. It is probable that even the ages of twenty and twenty-four are too early for those persons whose development is uncommonly slow. But there are other cogent reasons for discountenancing early marriages, also drawn from the physiology of reproduction, to say nothing of the many reasons which might be urged on other grounds. 1. During the development of the body, all its energies are required in perfecting the various tissues and organs. There is no material to be spared for any foreign purpose. 2. The reproductive act is the most exhaustive of all vital acts. Its effect upon an undeveloped person is to retard growth, weaken the constitution, and dwarf the intellect.