Page:Scientia - Vol. X.djvu/127

Rh the correlation table. To determine definitely whether the basis of the heterogeneity is inheritance, recourse must be had to pedigree analysis in terms of individuals and of families. Of course it will be true in many cases in actual practise that general considerations make it a priori highly probable or even certain that the basis of an observed heterogeneity is inheritance. In such cases the coefficient of correlation, may be said to indicate the existence of inheritance, though not to measure its intensity. But the first and fundamental «demonstration» that a character is inherited in a given group of individuals must always rest upon some other basis than coefficients of correlation alone. The essential point here made regarding the inherent difficulty in the interpretation of correlation coefficients, has been very ably discussed recently by G. Udny Yule1. I am in entire agrementagreement [sic] with his position.

The general purpose of this digression regarding the study of inheritance has been to show by a concrete example how erroneous biological assumptions at the fundation may invalidate completely a whole line of biometrical reasoning, It is hoped that this discussion will emphasize the importance of the point made at the beginning, that it is necessary always to keep clearly in mind the limitations of the biometric method in general. Biometry furnishes a valuable and refined extension of the descriptive method. Its future usefulness to biology depends largely upon a clear recognition of two things. These are, on the one hand, that biometric methods are, in their essential nature, purely descriptive methods of investigation, and, on the other hand, that for the valid employment of these methods, it is necessary to use as much general «biological intelligence» in regard to the significance of the biological problem attacked, the biological validity of the assumptions made in applying mathematical methods to the problem, and the applicability of the particular methods used to the particular problem studied, as would be exercised in any investigation by any other method.


 * Orono, Maine, JJ. 8. A. Biological Laboratory. Maine Experiment Station.

Raymond Pearl