176 MUTATION 



" The * London ' gooseberry (which, in 1852, had al- 

 together gained 333 prizes) has, up to the present year 

 of 1876, never reached a greater weight than that at- 

 tained in 1852. Perhaps the fruit of the gooseberry 

 has now reached the greatest possible weight, unless, in 

 the course of time, some new and distinct variety shall 

 arise." 



De Vries could not have put it better. 



MUTATION AND NATURAL SELECTION 



But, it is objected, the origin of characters by- 

 mutation can not account for adaptation as well 

 as quantitative selection; and adaptation is the 

 preeminent fact in nature. There is no good 

 reason for drawing such a contrast. For the 

 theory of mutation is nowhere incompatible with 

 that of Natural Selection; there may just as well 

 be, there just as truly is, a selection among dis- 

 continuous variations as among quantitative va- 

 riations. In the modern classification of varia- 

 tions selection has come to be associated with 

 quantitative variations; but Darwin did not al- 

 ways so associate it, as I have tried to show. Any 

 variation, of any kind or degree, must stand the 

 test of fitness to survive. If it can not meet the 

 test it must be eliminated. In a field I had 300 

 young fowl, of which twenty per cent were of 

 mixed colors, and eighty per cent were either 

 white or black. Twenty-four of these birds were 

 killed by crows, and all the dead were either 

 white or black excepting one spotted white and 

 buff. The solid colors are mutants; being con- 



