62 MODES OF RESEARCH IN GENETICS 



IV 



Let us now turn our attention to the considera- 

 tion of the limitations of biometry as a branch 

 of biological science. There is, I think, funda- 

 mentally but one such limitation of a general 

 character. This arises out of the fact, already 

 mentioned, that biometrical methods of research 

 are, in last analysis, strictly and purely descriptive 

 in character. There are but two general ways of 

 acquiring and formulating a knowledge of nat- 

 ural phenomena. These are the descriptive 

 method on the one hand, and the experimental 

 method on the other hand. Biometrical methods 

 belong in the first of these categories. The only 

 thing which they are able to do is to furnish a 

 description, in quantitative terms, of existing 

 phenomena. This does not, of course, imply 

 that they are not useful aids in experimental 

 investigations. Indeed, it is just here that, in 

 the writer's opinion, biometry finds, in general, 

 its highest usefulness in biology. It is only de- 

 sired to emphasize the fact that biometric methods 

 are per se purely descriptive, and have the limi- 

 tations implied thereby. 



In actual biometric work the importance of 

 keeping clearly in mind the limitations and precise 

 significance of the methods used is great. To 

 reach biologically significant results one must 

 understand clearly just what is being measured 



