In deciding upon marriage, hereditary influences deserve careful consideration in respect alike of the family of the prospective husband and that of the prospective wife. For it is well established that the law of inheritance relates not only to the peculiarities of external configuration, to the features, the stature, the tint of the skin, but also that children inherit from their parents their mode of bodily development, the functional activity of their organs, the duration of their life, their predisposition to disease, and even their intellectual and moral qualities. As regards hereditary predisposition to disease, the most important are, as is well known, the predisposition to tuberculosis, that to malignant tumors, and that to mental disorders. Great disparity in the respective ages of prospective husband and wife entail various kinds of unsuitability for marriage. An elderly man who marries a young girl, even if he still possesses a certain amount of virility, is unlikely to procreate healthy and powerful children; and these latter for the most part will be weakly, scrofulous cachectic, endowed with deficient powers of resistance, and often badly equipped from the intellectual standpoint. Similar considerations prevail in respect of marriages in which the husband has been exhausted by earlier sexual excesses, so that he retains no more than remnants of virility, whilst his semen is of doubtful fertilizing power. _D. Richard_ relates that Louis XIV asked his physician why it was that the children he (the king) had by his wife were delicate and deformed, whilst those he had by his mistresses were beautiful and powerful. “Sire,” was the answer, “c’est parce que vous ne donnez à la reine que les rincures.” _Plato_ maintains that before every marriage the man and the woman should both undergo official examination to determine their fitness or unfitness for the married state, the man being absolutely nude, and the woman stripped to the waist, for the examination. This author goes so far as to regard it as “a form of homicide for a man to embrace a woman when he is incapable of fertilizing her.” How rarely it happens in our day, however, that the physician, the official with the requisite knowledge to fulfil _Plato’s_ requirements, is asked for his opinion regarding the desirability of a contemplated marriage! The only occasion on which this is likely to occur is when a man intending to marry wishes to be assured that he is completely cured from an earlier infection with syphilis, and, therefore, runs no risk of transmitting the disease to his wife or to possible offspring. But it never occurs to the parents of a girl about to marry to ask the physician whether she is physically suitable for marriage.