No. 554] SHORTER ARTICLES AND DISCUSSION 1 1 7 



by the title of this paper, an analysis of the evidence presented 

 and its possible interpretation supplies the chief incentive for 

 this review. 



The greater part of this paper consists of a discussion of cer- 

 tain criticisms directed against the mutation theory by those 

 who believe that O. Lamarclnana is of hybrid origin. Certain 

 objections of Stomps appear to the writer well founded, 

 but we shall not take the space to consider this portion of the 

 paper since the greater interest attaches to the value of the direct 

 evidence offered by him in support of the mutation theory. 



When we come to the short account of the experimental work 

 of Stomps we find that the so-called "mutants" were not de- 

 rived from the pure Dutch biennis of the sand dunes but from 

 a cross between this race and a type designated 0. biennis cruci- 

 ata. This fact seems to the writer of fundamental importance 

 in judging the conclusions of Stomps. It should be made clear 

 that the form "0. biennis cruciata" is recognized in the more 



guished from types of biennis by its floral characters. What- 

 ever may have been the origin of 0. cruciata or its possible 

 relationship to 0. biennis, a cross between these types must cer- 

 tainly be regarded as a cross between two very distinct evolu- 

 tionary lines and its product a hybrid in which marked modifica- 

 tions of genniii.il i-nnMiliitiuii are to be expected. 



CEnothera cruciata differs from 0. biennis most conspicuously 

 in having very narrow linear petals, from 1-3 mm. wide, in sharp 

 contrast to the broad heart-shaped petals characteristic of 

 biennis. O. cruciata is found wild in certain regions of New 

 England and New York and is consequently a native American 

 species. Stomps assumes that the cruciata in Holland is a mu- 

 tant from the Dutch biennis, but his belief rests upon no direct 

 evidence. Cruciata has never appeared in the extensive cultures 

 of the Dutch biennis grown by De Vries and Stomps. Neither 

 have we any direct evidence that the American cruciata has 

 come from any form of biennis. It is true that the species 

 cruciata and biennis appear to be closely related, but it is 

 equally clear that they constitute very distinct lines each with a 

 long period of evolutionary independence. I can not see the 

 justification for Stomps's attitude when he treats a cross between 

 tbe biennis and cruciata of the sand dunes of Holland as though 

 !t were the combination of forms within the same species which 

 have similar germinal constitutions. 



