100 DARWINISM AND HUMAN LIFE 



so Protean that biologists tended to draw upon 

 the variability account as if there was no limit 

 to it, scarce waiting to see whether their cheques 

 were honoured. A lesson might have been taken 

 from Darwin's painstaking study (1868) of varia- 

 tions in domesticated animals and cultivated 

 plants, or from Mr, J. A. Allen's pioneer work 

 (1871) in measuring American birds, but the 

 vice of simply postulating variations when they 

 were wanted for theoretical purpose persisted 

 and has been wide-spread for fifty years. 



In the preface to his " Materials for the Study 

 of Variation " (1894), Bateson wrote : " We are 

 continually stopped by such phrases as, ' if such 

 and such a variation then took place and was 

 favourable,' or, ' we may easily suppose circum- 

 stances in which such and such a variation, if 

 it occurred, might be beneficial,' and the like. 

 The whole argument is based on such assumptions 

 as these — assumptions which, were they found 

 in the arguments of Paley or of Butler, we could 

 not too scornfully ridicule. ... If we had before 

 us the facts of variation there would be a body 

 of evidence to which, in these matters of doubt, 

 we could appeal. We should no longer say * If 

 variation take place in such a way,' or ' If such 

 a variation were possible ' ; we should, on the 

 contrary, be able to say, * Since variation does, 

 or at least may, take place in such a way,' 

 ' Since such and such a variation is possible,' 

 and we should be expected to quote a case, or 

 cases, of such occurrence as an observed fact." 



In the most general terms it may be said that 

 one of the greatest steps of progress in evolution- 

 lore since Darwin's day has been the accumulation 



