792 Fluctuations 



uct of the whole field. Rimpau, who has made 

 a thorough study of this evil and has shown its 

 dependency on various external conditions, has 

 also tried to find methods of selection with the 

 aim of overcoming it, or at least of reducing it 

 to uninjurious proportions. But in these ef- 

 forts he has reached no practical result. The 

 annuals are simply inexterminable. 



Coming to the alternative side of the problem 

 it is clear that annuals have always been ex- 

 cluded in the selection. Their seeds cannot be 

 mixed with the good harvest, not even accident- 

 ally, since they have ripened in a previous year. 

 In order to bear seeds in the second year beets 

 must be taken from the field, and kept free 

 from frost through the winter. The following 

 spring they are planted out, and it is obvious 

 that even the most careless farmer is not liable 

 to mix them with annual specimens. Hence we 

 may conclude that a strict and unexcelled proc- 

 ess of selection has been applied to the destruc- 

 tion of this tendency, not only for sugar-beets, 

 since Vilmorin's time, when selection had be- 

 come a well understood process, but also for 

 forage-beets since the beginning of beet- 

 culture. Although unconscious, the selection of 

 biennials must have been uninterrupted and 

 strict throughout many centuries. 



It has had no effect at all. Annuals are seen 



