Horticultiwal and Systematic Varieties. 57 



place the progressive origin of species, that formation of 

 new characters to which in the main the evokition of the 

 plant kingdom is due. On the other hand there is a 

 whole series of other types which are now, so far as it 

 is possible to judge, mainly confined to the lateral branches 

 of the phyletic tree. With regard to these however we 

 must content ourselves at present with indirect methods 

 of investigation. 



Darwin's statement that varieties are incipient spe- 

 cies is well known. So also are the words of one of the 

 most famous authorities^ on horticulture, Verlot : Toiite 

 variete a d\ihord existe a I'etat de variation. These two 

 generalizations are evidently based on phenomena en- 

 tirely different from those with which we have become 

 familiar in Oenothera. They constitute, so to speak, 

 the other extreme of the series. 



I propose therefore now to investigate the manner in 

 which ^Variations" in the sense of so-called structural 

 abnormalities or anomalies (and not the individuals which 

 exhibit variation in accordance with Ouetelet^s law) 

 arise, and how they result in the origin of ''species." 

 But here we come across an obstacle on the very threshold 

 of the inquiry in the manifold meanings of the word 

 variety.^ It will soon become clear that horticultural 

 and systematic varieties are to be considered as categories 

 of entirely different values. But both Darwin's and 

 Verlot 's sentences just quoted are based on data ob- 

 tained from horticultural varieties; and we must now 



^ B. Verlot, Production ct fixation dcs varictcs, 1865, p. 100. 



^The general conception of this term is that formulated by Car- 

 RiERE in the following words: "On nomnic varictc tout iudiridu qui, 

 par quclquc caractcre que ce soit, sc distingue d'lin ou de plusieurs 

 atitres avec lesquels on le compare et qu'on considere comme apparte- 

 nant a un mcme type specifique {Production et fixation des varictcs, 

 1865, p. 6). 



