occur. It was only after Raymond Pearl's masterful experimental analysis of fecundity in fowls into its three physiological unit characters, and his combining of the three units into one individual, that it was possible to secure a strain in which high fecundity was a fixed character. In breeding humankind the manipulation of unanalyzed qualities might prove as futile as the earlier experiments at the University of Maine. On the other hand Burbank, in his breeding experiments, has reached some permanent results, though he has never scientifically analyzed into their units the desirable qualities he has succeeded in combining and fixing. But in each case he has dealt experimentally with many thousands of individuals and has reached success in but a small proportion of his attempts. His methods offer little chance of success in human breeding.
Even one wholly unfamiliar with the subject can see at once that the mere outlining of the biological problems of eugenics and evolution is wholly impossible in a limited paper such as this. Yet this very fact points the chief moral I wish to urge.
We are at the very beginning of our knowledge of heredity. Few of the myriad of unit qualities in mankind, or other animals, have been identified and defined. We know some, perhaps all, the units of hair color and eye color, we know some of the units of shape of hair, and a few other such comparatively simple qualities. But, as yet, we are merely entering the pass that opens on to the broad fields of knowledge of inheritance. We have analyzed a mere handful of the simpler physical unit qualities. We know nothing, as yet, of psychic unit qualities. We can not even be positive that the inheritance of psychic qualities is by definite units which follow the so-called Mendelian laws of inheritance. That intellectual qualities, and moral stamina, are heritable seems indicated, but the parallelism between their mode of inheritance and that of such a thing as hair color, however probable, is as yet not definitely demonstrated. It is possible that most psychic qualities are too complex ever to be sucessfully and completely resolved into their heritable units.
How much progress, then, may we hope for. We don't know, and we can not know, until we have had decades, perhaps centuries, of further study of these most intricate problems. By the biologist, trained through the study of evolution to think in geologic epochs rather than years, the dawn of a new day for mankind is foreseen. But to the sociologist, whose chief business is to apply our knowledge to present conditions, the whole subject is of much more limited interest. Aside from a few very limited aspects of negative practise of eugenics, the whole subject is, as yet, of little social significance. The prolonged labor of hundreds of special students is needed before this matter, which already is of the keenest biological interest, can become of the
