Page:Scientia - Vol. X.djvu/122

114 has some meaning and interest. Just here is where so much of the biometrical work which has been done has failed. Too often has there been an espousal of the forlorn hope that the application of biometric methods might inject biological interest and meaning into a «problem » previously quite destitute of these attributes.

Further it is of the highest importance for the correct application of biometric methods to understand thoroughly the biological implications of the particular method employed. Failur e to do this is bound to lead one into all sorts of pitfalls. It has been a very unfortunate boast of some biome- tricians that their methods involved no biological assumption or implication whatever. Such a statement is seen upon critical examination, to be a logical absurdity. Biometric methods, « considered solely as pure mathematical reasoning », certainly have no biological implications, but the moment they are « applied » to biological data for the solution of biological problems they do carry biological implications. Otherwise their application is altogether irrational and futile. If no biological meaning or implication attaches to the determination of the degree of correlation between parent and offspring, for example, it is evidently a waste of time to calculate such correlations. Further, if it cannot be clearly shown that the method of determining such correlations is such as to lead to a « biologically » valid result, the application of the method in biology is equally idle. As the point here under consideration is one of fundamental importance, it will be well to give it full discussion with a concrete illustration.

It has been frequently maintained by Pearson that the «law of ancestral inheritance », which states that the correlation between offspring and their ancestors decreases in a geometrical progression as the number of included ancestral generations increases, involves no biological implication whatever regarding inheritance. Further it has been stated on the same authority that the method by which this «law » is deduced (namely by determining the correlations which exist between offspring and their ancestors) is valid whatever may be the biological basis or mode of inheritance. Now, as a matter of fact, practically all of the work which has been