It is only of late years that the eugenic importance of a considerable interval between births has been fully recognized, as regards not only the mother--this has long been recognized--but also the children. The very high mortality of large families has long been known, and their association with degenerate conditions and with criminality. However, of recent years, evidence has been obtained that families in which the children are separated from each other by intervals of more than two years are both mentally and physically superior to those in which the interval is shorter. Investigators have found that children born at only a short interval after the birth of a previous child are notably defective, even at the age of six, in a large percentage of cases; and when compared with children born at a longer interval, or with first children, they are, on the average, three inches shorter and three pounds lighter. These are facts of the most vital significance. Thus when we calmly survey, in however summary a manner, the great field of life affected by the establishment of voluntary human control over the production of the race, we can not see a cause for anything but hope. It is satisfactory that it should be so, for there can be no doubt that we are here facing a great and permanent fact in civilized life. With every rise in civilization, indeed with all evolutionary progress whatever, there is what seems to be an automatic fall in the birth-rate. That fall is always normally accompanied by a fall in the death-rate, so that a low birth-rate frequently means a high rate of natural increase, since most of the children born survive. Thus in the civilized world of today, notwithstanding the low birth-rate which prevails as compared with earlier times, the rate of increase in the population is still appalling--nearly half a million a year in Great Britain, over a million in Austro-Hungary, and three-quarters of a million in Germany. When we examine this excess of births in detail we find among them a large proportion of undesired and undesirable children. There are two alternative methods working to diminish this proportion: the method of regulating conception under the methods of scientific Birth Control, or the bungling substitutes for the same, on the one hand, and the method of preventing live births after conception by means of the abominable practice of abortion.