MUTATION 173 



(Loxia), crest (cardinal bird and jay), greatly- 

 elongated tail (widah bird), bare throat (bell 

 bird) , wattle (huia bird of New Zealand) , barb- 

 less feather shaft (paradise birds), barbs with- 

 out barbules (emu- wren), twisted feathers (Chi- 

 rocylla). The plumage may be glossy black, 

 snowy white, or of broken colors. Since such 

 characters have arisen suddenly, by mutation, 

 in poultry it is fair to conclude that they have 

 probably done so in other birds. Of course there 

 are many characters found in wild birds that are 

 not found in poultry, but where we have evidence 

 that many characters have arisen suddenly, dis- 

 continuously, it seems probable that many others, 

 of the same general sort, whose origin can not 

 possibly be known have arisen in the same way. 

 The experimental demonstration of the mutative 

 origin of many characters makes probable such 

 an origin for characters beyond the pale of ex- 

 perimentation. 



MUTATION VS. SUMMATION OF FLUCTUATIONS 



There are many who are quite willing to admit 

 that mutations do occur, but hold that the part 

 they play must always be regarded as relatively 

 less important than the summation of fluctua- 

 tions. From this view the mutationist can ap- 

 peal to the results of experiment. Does the 

 breeder actually introduce new characters into 

 the organic world by summating fluctuations? 

 De Vries insists that the improvement that fol- 



