40 HEREDITY 



reconcile the conclusions of every school of workers 

 would therefore be not only futile, but premature. 

 The writer is thus compelled to choose some mean 

 between the impossible ideal of presenting a com- 

 plete account of an incomplete science and the 

 very unappetising device of stating, in isolated or 

 mutually contradictory chapters, the conclusions of 

 all the different groups of workers in this field. 

 The biometricians, however, with their distinctive 

 method and their complete independence from all 

 save mathematical preconceptions, do very definitely 

 demand this kind of treatment. 



The main object of this school is to treat the pro- 

 cesses of evolution quantitatively. When we use 

 terms like variation and selection, the biometricians 

 demand exact measurement of them : relative, of 

 course, but still exact. It is of no use to us, they 

 say, to be told that an organ is variable ; we must 

 know how it varies in a thousand individuals. It is 

 of no use to tell us that a race is long-headed ; we 

 must have exact measurements of the cephalic index 

 in a thousand individuals of that race. ... Of course 

 it is obvious that a very large number of biological 

 statements are in their essence statistical. The bio- 

 metricians have spent much labour upon the critical 

 examination of these statements. Indeed it may be 

 said that biometry is the application of the methods 

 of the "higher statistics" to biology. Workers in 

 many fields are beginning to discover that in the 

 absence of mathematical training they are hicom- 

 petent justly to appraise any of their statistical or 

 quantitative results. It is thus a most satisfactory 

 sicrn of the times that medical men, for instance, 



