No. 539] ORIGIN OF SPECIES IN NATURE 



fi49 



rayflowers, the white coloring disappeared from view. 

 It is an instance of change of color analogous to that of 

 the cactus dahlia, though differing in one striking fea- 

 ture. For in the latter case the brilliancy of the flowers 

 is due to the recurved rayflorets which show the bright 

 color of the upper surface instead of the dull shade of the 

 lower one, exposed to view in the older form of dahlia. 



The plant was segregated and propagated vegeta- 

 tively, as many as one hundred specimens being on hand 

 at a time. Among these not a single instance of a return 

 to the conventional form was observed. Of course, it 

 would have been far more interesting to note the result 

 of sexual propagation, a proceeding which was rendered 

 impossible by the failure of the flowers to produce good 

 seed. This, however, is quite in accordance with the 

 experience of horticulturists, fide Andre. 20 In this most 

 comprehensive publication the variety discoidea is men- 

 tioned under the name of "Paquerette vivace var. 

 double a fleurs tuyautees," its slight fertility noted and 

 attention called to the fact that the seed for such plants 

 must be collected from flowers which are almost double. 

 It is added: "leur tendance a doubler est assez bien fixee 

 pour qu'on ne trouve dans le semis presque pins do flours 

 de duplicative imparfaite." In this connection Master's 

 notes published in the appendix to his "Vegetable 

 Teratology,'' and de Vries's remarks on Mat thiol a 

 incana fl. pi* are of considerable interest. Penzig evi- 

 dently refers to a similar form, 22 though his use of the 



