COBB AND BARTLETT: INHERITANCE IN OENOTHERA 463 



They have given rise to a number of interesting mutations, one 

 of which, mut. nummularia, is especially conspicuous in the young 

 seedling stage because of its orbicular leaves, and was on that 

 account the first to receive intensive study. ^ In general, the 

 mutations of the relatively stable strains belong to two types, 

 (a) those that come true when self -pollinated and show matro- 

 cHnic inheritance in crosses with the specific type (e. g., mut. 

 nummularia) and, (b) those that split in every generation into 

 the mutational type and the specific type, regardless of whether 

 they are self -pollinated or polHnated by the specific type. The 

 latter are similar to Oenothera stenomeres mut. lasiopetala^ and to 

 certain mutations from Oenothera Lamarckiana described by 

 de Vries.^ 



A strain of Oenothera pratincola differing from all the rest has 

 been designated as Lexington B. It has given rise to some, but 

 not all, of the mutations thrown by the other strains, and in 

 addition it has produced in large numbers a series of character- 

 istic mutations having certain characters in common that are 

 not met with among the mutations of the other strains. These 

 characters are revoluteness of the leaves and the possession of a 

 peculiar subterminal filiform appendage on the lower surface 

 of the leaf, into which the midvein is diverted. All of the charac- 

 teristic mutations of the mass-mutant strain, Lexington E, come 

 true, whether self-polHnated or pollinated by the f. typica of 

 strain K. To be more precise, they come true in the sense that 

 they do not revert, in part of each generation, to f. typica, al- 

 though they may be very highly mutable, and give rise to other 

 members of the revolute-leaved series of mutations. 



In brief, there are relatively stable strains of Oenothera pratin- 

 cola, such as Lexington C, which throw small numbers of flat- 

 leaved mutations belonging to several kinds, one of the most 



' Bartlett, H. H. Additional evidence of mutation in Oenothera. Bot. Gaz. 

 59: 81-123. 1915. 



* Bartlett, H. H. The mutations of Oenothera stenomeres. Amer. Journ. 

 Bot. 2: 100-109. 1915. 



^ DE VriES, Hugo. New dimorphic mutants of the Oenotheras. Bot. Gaz. 62 : 

 249-280. 1916. 



