the convicts in his Majesty's prisons, serve to increase the total data already available or nearly so. While all eugenics workers crave for more material, and for better quality of material, yet there already exists ample material upon which to base the beginnings for our science.
If we turn from material to method, we note that except in so. far as results for animals have application to man, we can not experiment on individuals, and our methods must, therefore, be those applicable to mass-observations—that is to say, those actuarial methods applied to biological data which we now term the methods of biometry. It is not needful for me to enlarge now or here on those methods. Suffice it to say that they appear to measure effectively the relationship between factors which are not causally linked together. For the explanation of what follows I would state that the arithmetical value of a certain quantity—the so-called coefficient of correlation—is chiefly used to measure this relationship. Starting when the quantities are absolutely independent with zero value, it rises with their complete causal relationship to unity. Table I. shows the sort of values taken by this coefficient for various kinds of association, when the variates lack the absolute dependence of pure causation.
| Table I. | |
| Correlation Coefficients | |
| High Correlation 1 to.75 | |
| Right and left femur in man | .08 |
| Finger and forearm in man | .85 |
| Foot and forearm in man | .80 |
| Middle phalanges of middle and little finger | .76 |
| Considerable Correlation .75 to .5 | |
| Weight and stature in woman | .72 |
| Finger and stature in man | .66 |
| Vaccination and recovery in cases of smallpox | .60 |
| Weight and strength of pull in man | .55 |
| Moderate Correlation .5 to .25 | |
| Forearms of two brothers | .40 |
| Deviations in bank reserve and discount rate | .37 |
| Coat color in horse and its grandsire | .30 |
| High barometer in Portugal and low barometer in Norway | .27 |
| Low Correlation .25 to .00 | |
| Resemblance of Aphis to its grandmother | .24 |
| Size of family, mother and daughter | .21 |
| Duration of lives, mother and daughter | .15 |
| Length and breadth of Parisian skulls | .05 |
From method I turn finally to illustrate the nature of the conclusions which have already been reached by eugenic inquiry. As a preliminary, I must picture for you what I think evolution means in the case of human societies.
There was a time when, thinking over the marvelous intellectual,
