404 Origin of Each Species Considered Separately. 



the commonest mutants, and at the same time one of the 

 most easily recognizable in its early stages. It appeared 

 229 times in the main line of the Lamar ckiana-id.m\\y 

 (p. 224), in the branch family 171 times, in the laevi- 

 /o/m-family 9 times and very frequently in other cultures 

 too. I have cultivated many such mutants until they 

 flowered and set seed ; in every case they conformed ex- 

 actly to a common type. 



No separation of the characters of the species has 

 been observed. Oenothera semilata (§ 17) which ap- 

 peared at first to be an instance of this, turned out to be 

 a distinct form. 



The characters of the species can be regarded as 

 distinct "groups," better in the case of O. lata, than in 

 the case of any other species. Each ''group" obviously 

 constitutes a unit, but how the existence of the separate 

 ''groups" is brought about by the same cause is as yet 

 unknown. Examples of these "groups" are, the form 

 of the leaves, the thick flower-buds, the lack of pollen, 

 the abnormal growth of the pistil, and the short fruits 

 w^ith relatively few seeds. 



Let us look at the leaves; they are crumpled, and 

 round at the tip ; the edge is too small for the area of the 

 leaf which is therefore much bent. The bracts are much 

 broader at the base than they are in the parent species. 

 The apices of the large branches and the smaller lateral 

 branches form peculiar little rosettes. A complete de- 

 scription would extend over a whole page of print and 

 need many figures. (Fig. 89.) Nevertheless it is certain 

 that all these units are intimately bound up with each 

 other and that they must owe their existence to the pres- 

 ence of a single factor. 



Perhaps this factor is the abnormally luxuriant super- 



