58 77k' Different Modes of Or'uj'ui of iicie Species. 



inquire how far tlieir transference to systematic varie- 

 ties is justified.^ 



Tlie origin of horticultural varieties will therefore 

 be submitted to a critical and experimental examination. 

 But before we do this I think it advisable to consider 

 first the meaning which is attached to the term variety 

 in systematic works, and secondly the various ways in 

 which species can arise. And we shall find that whilst 

 there is no question that the mode of origin of horti- 

 cultural varieties is often analogous to that of so-called 

 ''good" species, this parallel is by no means so common 

 as the present form of the doctrine of descent would lead 

 one to believe. 



To begin with systematic varieties : Here we find we 

 can draw a pretty natural line between what we called ele- 

 mentary species on the one hand, and real systematic 

 varieties on the other. 



In connection with this antithesis I think it desirable, 

 after what has already been said on this topic in the first 

 volume,- to lay especial stress on the fundamental dif- 

 ference between these two conceptions. Linnaeus and 

 his pupils describe the elementary species as varieties ; 

 Jordan, De Bary, and others who argue from experi- 

 mental data, refer to all forms as species. 



The terms ''species" and "variety" have become so 

 familiar that it is no longer possible to effect any radical 

 change in their definition. For their exact meaniu"- we 

 have to refer to the works of Linnaeus himself. His 



* For some interesting observations relating to the origin of new 

 forms, see the papers bv F. Krasan in Engler's BotauiscJic JaJir- 

 hUclicr, Vol. XIII. Pts. 3-4; Vol. XXVIII, Pts. i, 2 and 5. and also 

 his Mittlicilungcn iibcr Ciilturvcrsuchc mit Potcntilla arenaria, Graz, 

 1900. 



^ See Vol. I, § 7, "Species, Subspecies and Varieties," especially 

 pp. 169-172. 



