1914] DE VRIES—OENOTHERA LAMARCKIANA 347 
rank or even marked varieties, the mutationists would have much 
stronger evidence in support of the mutation theory than that 
based on the behavior of O. Lamarckiana.”4 After conceding this 
strong position to his adversaries, DAvis subjects the results of 
SToMPs to a rather sharp criticism, which, unfortunately, is based 
upon a confusion of two wholly distinct types, namely, O. biennis 
L. var. cruciata’ and O. cruciata Nutt. He says: “It should be made 
clear that the form (O. biennis cruciata) is recognized in the more 
recent taxonomic treatments as a true species sharply distinguished 
from types of biennis by its floral characters,” and “a cross between 
these types must certainly be regarded as a cross between two 
very distinct evolutionary lines and its product as a hybrid in which 
marked modifications of germinal constitution are to be expected.’ 
But, as a matter of fact, the Dutch O. biennis cruciate differs from 
O. biennis only in the characters of the petals; in all other respects 
it is wholly the same, and therefore evidently only a subordinate 
variety of this species. It has not been dealt with in recent 
taxonomic treatments, since it occurs almost exclusively in the 
sand dunes of Holland, where it is produced from time to time by 
Mutation from the mother form (first observed in 1900), without 
having been able until recently to multiply in the field so as to 
produce a persistent local variety.” 
On the other hand, O. cruciata Nutt. is quite a different species, 
with narrow, brownish green leaves, and a different type of branch- 
ing, of spikes, and of fruits. It grows wild in New York and 
Vermont, and is well known to all students of the American flora. 
By some authors it has been considered a variety of O. biennis, 
and this probably is the chief cause of Davis’ confusion. The 
character and the behavior of its hybrids with O. biennis have 
been amply dealt with in my Gruppenweise Artbildung. 
the experiment of Sromps, the dwarf and semigigas muta- 
ions were produced by hybrid strains of O. biennis and O. biennis 
‘Davis, B. M., Mutations in Oenothera biennis L.? Amer. Nat. 47:116-121 
€specially p. 116), 1913; see also of. cit. 47:540-596 (especially p. 567). 1913. 
‘ Die Mutations-Theorie 2: 599. 1903. 
* Amer. Nat. 477117. 1913. 
Die Mutations-Theorie 2: 599. 1903. 
