=Constructive Eugenics Must Be Based on Education.--=As to the first phase, direct selection for superiority, the campaign must, in the very nature of things, be one of education. With the necessary knowledge of the facts in mind, the awakening conscience of the individual together with an enlightened public opinion will form the safest guide. Increasing popular comprehension of the inevitable nature of human inheritance must engender a sense of responsibility as to the positive eugenic fitness of a contemplated marriage. The growth of this sentiment will doubtless be slow, and properly so, for as yet we have but half-lights on what are the most desirable types of humanity. No one can say what the highest type of man should be, but almost any one can readily pick out types which certainly should _not_ be. =Inferior Increasing More Rapidly Than Superior Stocks.--=Modern eugenists, although realizing that the constructive phase is of great importance, are making no attempt to map out any fixed mode of procedure for it beyond pointing out the desirability of larger families among the better classes. The need for individuals of superior physical, mental and moral qualities to multiply is so obvious as scarcely to require comment. Yet the fact is that judging from all appearances these are the very ones who have the lowest birth-rate. Eugenics is mainly concerned with the relative rates of increase of the various classes, not with mere fertility in itself. And the actual increase must be measured in terms of the extent to which birth-rate exceeds death-rate. If a high birth-rate is accompanied by a high death-rate then it is not especially significant in increasing a given class as a whole. All available evidence points to the fact that to-day the lower strata of society are far outbreeding the middle and higher, with an almost negligible difference in death-rate, and just in the measure that these lower strata are innately inferior just in that degree must the race deteriorate. The seriousness of the whole situation as it exists to-day hinges, therefore, on the extent to which the lower strata are inferior to those above them. =An Unselected Population May Contain Much Valuable Material.--=In evaluating these lower strata a matter of very great importance is whether the population is a selected or an unselected one. If the population has been long resident in a given region and has had fairly good opportunity for education then we will find in the lower reaches a larger percentage of sedimentation made up of the worthless and inferior stocks. If, however, a continual fomentation and geographical shifting of the population is in progress as in parts of America, or if adequate educational opportunities are lacking, as in some parts of Russia, the poor and less well-to-do classes may contain, no one can tell how much, relatively valuable stock. Forel remarks on this point as follows: