118 Ataz'isjii. 



science of variability and mutability, and especially in that 

 of atavism of which they perhaps afford the most beauti- 

 ful examples. As such they have been dealt with espe- 

 cially by Louis Vilmorin whose theory we will now pro- 

 ceed to examine.-^ 



Vilmorin starts from the observation that striped 

 flowers only occur on those species which are themselves 

 colored, but which also possess a white variety; or if the 

 color of the flower is composed of red and yellow the 

 uniform yellow variety may behave like the white {Mira- 

 hilis, Antirrhinuui). The first variety to arise is the 

 white (or yellow) from which later on the striped form 

 originates and Vilmorin explains this as a partial re- 

 A'ersion to the parent species. 



White varieties of a large number of decorative plants 

 have arisen in cultivation, and in fact many favorite ones 

 in M. Vilmorin's own nurseries. Thev can usuallv be 

 easily "fixed" in the course of a few years; that is to 

 say, they are generally constant from the very beginning 

 but have to be purged of the consequences of unavoidable 

 crosses, and this takes a few years, as a rule. The striped 

 sorts do not appear in this period, the hybrids resulting 

 from the crosses are like the parent species and segregate 

 into this and the pure white variety. The striping is not 

 the result of crossing therefore ; moreover in such cases 

 deliberate crossing has only resulted in the production 

 of self-colored and not of variegated flowers. Also, 

 when such hybrids exhibit sectorial variation, the color 

 is in large patches and not In fine stripes. 



It is not until the white varieties have attained com- 

 plete purity and have proved constant for a considerable 



"^ Soclcfc PhJloinafique de Pan's. Seance du 17 Janvier, 1852, Pro- 

 ecs-verbaux, p. 9; Notices sur ramelioraiion des plantes par le semis, 

 1886, p. 39 ; and B. Verlot, Sur la fixation des varietes, 1865, pp-62-66. 



