She has also instituted laws to prevent its undue increase. It would seem as if the extension of material mental and social comfort and culture has a tendency to render marriage less prolific, and population stationary or nearly so. So evident is this tendency, that it has been laid down as a maxim in sociology by Sismondi, that 'where the number of marriages is proportionally the greatest, where the greatest number of persons participate in the duties and the virtues and the happiness of marriage, the smaller number of children does each marriage produce.' Thus, to a certain extent, does nature endorse the opinions of those political economists who assert that increase of population beyond certain limits is an evil happily averted by wars, famines, and pestilences, which hence become national blessings in disguise. She, however, points to the extension of mental and moral education and refinement as gentler and surer means of reducing plethoric population than those suggested by Malthus and Mill. Many causes of sterility, it will therefore be seen, are beyond the power of man to control. They operate on a large scale for the good of the whole. With these we have little concern. But there are others which may be influenced by intelligent endeavor. Some have been already alluded to, and the remedy suggested; but we will proceed to give more specific ADVICE TO WIVES WHO DESIRE TO HAVE CHILDREN. It has long been known that menstruation presents a group of phenomena closely allied to fecundity. The first eruption of the menses is an unequivocal sign of the awakening of the faculty of reproduction. The cessation of the menstrual epochs is a sign equally certain of the loss of the faculty of reproduction. When conception has taken place, the periodical flow is interrupted. Labor occurs at about the time in which the menses would have appeared. In short, it is a fact, now completely established, that the time immediately before, and particularly that after the monthly sickness, is the period the most favorable to fecundation. It is said that, by following the counsel to this effect given him by the celebrated Fernel, Henry II., the King of France, secured to himself offspring after the long sterility of his wife before referred to. Professor Bedford, of New York, says that he can point to more than one instance in which, by this advice, he has succeeded in adding to the happiness of parties who for years had been vainly hoping for the accomplishment of their wishes. Repose of the woman, and, above all, sojourn on the bed after the act of generation, also facilitates conception. Hippocrates, the great father of medicine, was aware of this, and laid stress upon it in his advice to sterile wives.