186 Retrograde Varieties 



formerly active, and awaiting probably through 

 centuries an occasion to awaken, and to dis- 

 play the lost characters. 



Cases of apparent reversion were often seen 

 in nurseries, especially in flower culture, which 

 under ordinary circumstances are rarely 

 wholly pure, but always sport more or less into 

 the colors and forms of allied varieties. Such 

 sporting individuals have to be extirpated 

 regularly, otherwise the whole variety would 

 soon lose its type and its uniformity and run 

 over to some other form in cultivation in the 

 vicinity. For this reason atavism in nurseries 

 demands much care and labor, and consequently 

 is to be dealt with as a very important factor. 

 From time to time the idea has suggested 

 itself to some of the best authorities on the 

 amelioration of plants, that this atavism was 

 not due to an innate tendency, but, in many 

 cases at least, was produced by crosses between 

 neighboring varieties. It is especially owing 

 to Verlot that this side of the question was 

 brought forward. But breeders as a rule have 

 not attached much importance to this supposi- 

 tion, chiefly because of the great practical diffi- 

 culties attending any attempt to guard the spe- 

 cies of the larger cultures against intermixture 

 with other varieties. Bees and humble-bees fly 

 from bud to bud, and carry the pollen from one 



