104 Selection Docs Not Lead to Origin of Species. 



mounted to 21%, and the other figures have risen cor- 

 respondingly. Commercial beet grown from this selected 

 seed, has on the average 13 to 14% sugar. 



Without underrating the high agricultural signifi- 

 cance of these results we must nevertheless face the fact 

 that there is very little in them which can serve as a 

 basis for a decision of the question of the origin of 

 specific characters. We cannot be certain whether after 

 selection for fifty years, i. e., for 25 generations, the 

 upper limit of the range of variability has been essentially 

 extended or not. It so happens that this limit — 21% — 

 is the same in Vilmorin's instance (1853) and in the 

 works at Naarden (1892-1898), but there are other 

 races under different conditions of cultivation, whose 

 limit is stated to be as high as 26%. The wider range 

 of modern polarization work with beets evidently gives 

 a chance of higher percentages. 



The average product of a field has certainly Increased 

 from 7-8% to 14-16% and more. But this improvement 

 is dependent on the continuation of selection; and it is 

 only by this means that it has reached this pitch. Every 

 sugar manufacturer knows that selection is an indis- 

 pensable condition of a satisfactory harvest. It is true 

 that, for the purpose of obtaining the necessary quantity 

 of seed, a so-called intermediate generation is inter- 

 ])olated between polarization and seed-harvest: but if 

 more than one or at most two (and this happens very 

 seldom) of these are introduced the advantage gained 

 by polarization and selection is lost. By no manner of 

 means is the improvement independent of selection; on 

 the contrary the promise of more sugar can only be 

 fulfilled by a further perfection of the method of polari- 

 zation and by continued efforts on the part of breeders. 



