BREEDING AND HEREDITY 9 



the same set of characters — the red colourinff, the 

 brittleness, the narrow leaves — but none of these 

 characters ever appeared separately. It also, like 

 0. gigas, produces offspring, all of which are indis- 

 tinguishable from itself. 



(Enothera nanella, — This is the dwarf (EnotJiera, 

 A whole plant is shown in Fig. 5. It does not 

 attain to half the stature of the parent form. It 

 arose 158 times during the whole course of the 

 experiments, during which some 50,000 plants were 

 raised, i.e. it appeared in a ratio of about 3 per 

 cent. It also, like the other two new species already 

 mentioned, came perfectly true to seed directly it 

 had arisen. 



0. nanella is distinguished from the other new 

 species which I have described, fii'st in the fact that 

 it differs from its parent species by only one salient 

 feature — dwarfncss ; and secondly in the fact that this 

 characteristic is commonly found in other genera of 

 plants, as for instance the pea (see Fig. 6), to mention 

 one of a large number of plants which present this 

 peculiarity. Professor de Vries has proposed to give 

 the name " varietal " to characters like dwarfness, 

 which are widely distributed throughout the vege- 

 table kingdom, to distinguish them from specific 

 characters which, according to him, do not recur in 

 this way. Varieties ar^ forms characterised by the 

 possession of varietal characters, and species are 

 forms characterised by specific characters thus 

 defined. For instance, the complex of characters 

 possessed by 0. gigas or by 0. ruhrinervis do not occur 



