We shall not be surprised, then, if we find other {261} such biological checks and compensations exerting themselves. In recent years Sir Francis Galton, the cousin of Darwin, who is recognized as the best living authority in statistical biology, and Professor Karl Pearson, who has done more than any one else to bring out many curious and interesting but very important biological laws by the study of statistics, have insisted in their studies of the effect of the law of primogeniture, that when there are small families, the children are more likely to be nervous, oftener have an inclination to mental disease and have less resistive vitality against disease in general than the average child of the larger families. There is a small but significant advantage in vitality that accrues to later children of a family. This is so contrary to the frequently expressed opinion that only the children of small families can be brought up properly to resist disease and have such advantages in their education and nutrition as to be of better health, that I should hesitate to quote it, only that it has behind it the authority of such distinguished scientists as Galton and Pearson. They are both conservative Englishmen, they have no theory of their own that they are supporting, they have no axe to grind in things social and political for the launching of the new theory, they are only making observations on the facts presented and the data that have been collected. Here is another striking example of a check on certain tendencies in humanity that apparently {262} nature does not approve of, or to avoid personifying a process, we had better say are not according to nature's laws. The small family does not perpetuate itself. It has certain natural disadvantages that work against it. It gradually disappears and the races of larger families maintain themselves. We need not have had recourse to Galton's and Pearson's principle in this matter, for we see the results of the small family in present-day history. France is decreasing in population. Our own Puritan families are dying out. American families generally of more than three generations are not perpetuating themselves. The teeming fertility of the poor immigrants who come to us is, with immigration itself, supplying our increase in population. Our nation is, as a result, gradually becoming something very different from what our forefathers anticipated.