Page:Popular Science Monthly Volume 79.djvu/187

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existence of heredity in man. It is still urged by some that in the mental qualities nurture is of far greater importance than nature. So at the time when he struck out in a new direction in biology it was by no means obvious that heredity—to say nothing of the laws of inheritance—was common to man and the lower organisms. Our present belief that this is true is largely due to the labors of Galton and his school.

Again we must remember that even in "Hereditary Genius" he had definitely in view the possibility of race improvement. However unsuited human material may be for unravelling recondite laws of inheritance, it must be admitted that from its high sociological importance the problems of heredity and environmental influence must be investigated in the human species.

To discuss Galton's work on inheritance in greater detail at the present time would be a thankless task, for his immense service to the science of heredity and the great value of his methods for some problems of inheritance have been generally obscured by the enthusiasm over other means of attack. With a little time and a bit of Galtonian patience we shall perhaps arrive at a saner point of view than that now prevailing.

Galton's application of quantitative methods to the problems of human faculty and heredity is one of the forces which has gone into the formation of the biometric school of biologists. His influence in connection with this school is his greatest service to biology.

It may not be amiss to state here what the fundamental articles of faith of the biometrician are. They seem both simple and highly reasonable.

First, the biometrician requires that all observations shall be reduced, in so far as the material permits, to a quantitative basis. Gallileo's injunction to measure what is measurable and to render measurable what is not, must become the ideal of biologists, as it has long been of physicists, chemists and astronomers. "When a sufficient number of biologists have made this the guiding principle of their work, the hoary and decrepit distinction between precise and biological sciences will pass away.

Second, the biometrician insists that generalizations be drawn only from adequately large series of observations. The living substance is so subject to as yet unknowable, or at least immeasurable, influences that we dare not trust the "individual instance "; it is only upon a large number—and sometimes a very large number—of individual instances that conclusions of value may be drawn.

Third, the biometrician demands that the actual data, quantitative in quality and adequate in amount, shall be interpreted by sound logic. The most suitable logic, he believes, is that of the mathematician. This is agreed upon in theory by the most severely and variously disciplined