New Species of Oenothera 537 



quite constant from the very first moment of 

 their appearance. I have cultivated them from 

 seed in large numbers, and they have never re- 

 verted to the lamarchiana. From this they 

 have inherited the mutability or the capacity of 

 producing at their turn new mutants. But they 

 seem to have done so incompletely, changing in 

 the direction of more absolute constancy. This 

 was especially observed in the case of ruhri- 

 nervis, which is not of such rare occurrence as 

 0. gigas, and which it has been possible to study 

 in large numbers of individuals. So for in- 

 stance, " the red- veins " have never produced 

 any dwarfs, notwithstanding they are produced 

 very often by the parent-type. And in crossing 

 experiments also the red-veins gave proof of the 

 absence of a mutative capacity for their produc- 

 tion. 



Leaving the robust novelties, we may now 

 take up a couple of forms, which are equally 

 constant, and differentiated from the parent- 

 species in exactly the same manner, though by 

 other characters, but which are so obviously 

 weak as to have no manifest chance of self- 

 maintenance in the wild state. These are the 

 whitish and the oblong-leaved evening-prim- 

 roses or the Oenothera alhida and oblonga. 



Oenothera alhida is a very weak species, with 

 whitish, narrow leaves, which are evidently in- 



