72 MODES OF RESEARCH IN GENETICS 



tions at the foundation 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 limi- 

 tations of the biometric method in general. 

 Biometry furnishes a valuable and refined exten- 

 sion of the descriptive method. Its future use- 

 fulness 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 investiga- 

 tion, 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, 

 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. 



