VOLUME LXII NU.VIKKK 4 



THE 



Botanical Gazette 



OCTOBER 1916 



NEW DIMORPHIC MUTANTS OF THE OENOTHERAS 



Hugo DeVries 

 (with five riGURES) 



Among the previously described mutants of Oenothera Lamarck- 

 iana Ser. there is a form which, although fertile with its own pollen, 

 yields a dimorphic progeny. Some of the individuals exactly 

 repeat the stature and characters of their' parent, but others return 

 to the type of 0. Lamarckiana. Besides these, new mutants, 

 especially O. ohlonga, are relatively numerous. The two main 

 types are produced in varying proportions, according to the indi- 

 vidual cultures. The typical specimens may be as few as lo per 

 cent, or as numerous as 80 per cent. In most instances, however, 

 they show a proportion of about 35-40 per cent. Considering the 

 much smaller individual strength of the typical ones, as compared 

 with the atavistic specimens, these figures may be regarded as 

 indicating a sphtting, ordinarily, into nearly equal parts. 



This inconstant mutant is 0. scintillans.^ Exactly the same 

 phenomenon of splitting has been observed recently in a number 

 of new types. In the first place, in 0. stenomeres mut. lasiopetala, 

 described by Bartlett.^ In the second place, it has occurred in 

 my own cultures, among the new mutants of 0. Lamar ckian.a, as 

 well as among those of another American species, described under 



'The mutation theory. Chicago. 1909. Vol. I, p. 377; and Gruppenweise 

 Artbildung, p. 257- 1913- 



'Bamlett, H. H., Mutations of 0. stenomeres. Amer. Jour. Bot. i: 100-109; 

 see also 2:146. 1915. 



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