BIOMETBIC IDEAS AND METHODS 59 



would be quite unable to attack a whole series of 

 interesting and fundamental problems of mor- 

 phogenesis. Such problems, for example, as the 

 precision of morphogenetic localization, or the 

 degree of variability of successively regenerated 

 structures (does the morphogenetic mechanism 

 learn to work better with practice?), or the exist- 

 ence and nature of fundamental laws of growth 

 determining the general features of the tectonics 

 of large groups of plants and animals, etc., demand 

 the application of biometric methods if they are 

 to be adequately treated. There is a host of 

 problems of morphogenesis of this general charac- 

 ter as yet hardly touched at all by the biologists. 

 Biometric methods which enable us to deal with 

 groups of things or events as groups furnish the 

 key to the successful attack on these problems. 

 Pioneer work in this direction is being done, but 

 there is a vast and fertile field here, the proper 

 cultivation of which will demand the combined 

 efforts of many workers. To the application of 

 appropriate biometric methods in this field we 

 may confidently look, I think, as the source of a 

 significant advance in the building up of a science 

 of causal morphology. 



The second fundamental contribution of biom- 

 etry to biology lies in the fact that it has shown, 

 and in the future will still more impress upon the 

 biologist, the significance and great importance 

 in all his work of the probable error concept. 



