BIOMETRY AND EXPERIMENT 141 



they are mistaken, the truth would have been all the more 

 thoroughly proved had a completer use been made of the biometric 

 data had the biometric conclusions (of which the principal is the 

 hypothesis that evolution is founded on small variations, ' fluctua- 

 tions ' as they are called, not on mutations or sports) been linked 

 up with and tested by conclusions which are disputed by nobody 

 and are founded on facts, also undisputed, gathered by simple 

 observation. 



