False Atavism 193 



paths, as I have seen at Erfurt in the case of 

 numerous varieties of the Indian cress or Tro- 

 paeolum. 



Each variety is purified at the time when it 

 shows its characters most clearly. With vege- 

 tables, this is done long before flowering, but 

 with flowers only when in full bloom, and with 

 fruits, usually after fertilization has been ac- 

 complished. It needs no demonstration to show 

 that this difference in method must result in 

 very diverging degrees of purity. 



We will confine ourselves to a consideration 

 of the flowers, and ask what degree of purity 

 may be expected as the result of the elimination 

 of the anomalous plants during the period of 

 blooming. 



Now it is evident that the colors and forms 

 of the flowers can only be clearly distin- 

 guished, when they are fully displayed. Fur- 

 thermore it is impossible to destroy every 

 single aberrant specimen as soon as it is seen. 

 On the contrary, the gardener must wait until 

 all or nearly all the individuals of the same va- 

 riety have displayed their characters, as 

 only in this way can all diverging specimens 

 be eliminated by a single inspection. Un- 

 fortunately the insects do not wait for this 

 selection. They fertilize the flowers from the 

 beginning, and the damage will have been done 



