Examples of Constant Races. 83 



constant varieties, based on data given b}' gardeners and 

 botanists as well as on his own observations.^ 



It is a common opinion amongst gardeners that white 

 flowered varieties are among the most constant. They 

 are very plentiful and easy to control. From the cases 

 as yet investigated it may be assumed that hybrids 1)e- 

 tween them and the colored species will be colored also, 

 and therefore soon and easily discovered ; so that in the 

 purification or fixation of these varieties the hybrids 

 are usually removed soon and altogether, wdiich is a 

 very important thing for approaching constancy. Sev- 

 eral investigators have tested the purity of white vari- 

 eties. For instance Hildebrand- worked with white 

 Hyacinths, Delphinium Consolida, Matthiola incana and 

 Lathyrus odoratus; Hoffmann with Linum nsitatissi- 

 mum album :^^ Hofmeister for thirty years with Dicjitalis 

 parz'i flora alba;^ Prehn with Scabiosa alba;^ etc. 



I myself have made similar observations. I started 

 by buying a few plants of each of some varieties of 

 perennial species, allowing them to flower on isolated 

 spots and then saving and sowing their seed. Wherever 

 the isolation w^as complete all the offsiring, with a single 

 exception (Aquilegia chrysanfha) , were white flowered. 

 The following were the species tested in this way (I give 

 in parentheses after each one the number of plants which 

 were raised from their seed and observed in flower) : Cam- 

 panula pyraniidalis alba (26) , C. pcrsicifoUa alba ( 1 044) , 



^ Irwin lynch, Tlie Evolution of Plants, Journ. Roy. Hort. Soc, 

 Vol. XXV, Pt. I, pp. 34-37, Nov. 1900. 



^ HiLDEBRAND, Die Favhcu dcr Bliithcn, p. 70. 



^ Hoffmann, Botan. Zcitung, 1876, p. 566. See also the very 

 complete list of constant white varieties given by Carriere, pp. 12-13, 

 and the literature cited there. 



* Hofmeister, Allgemeine Morphologic, p. 556. 



^J. Prehn, Schr. Nafurzu. Vereins Holstcin, Vol. X, 1895, p. 259. 



