

G. H. SHULL 89 



as having "pale red blotches " ; in my cultures that species had deep red 

 blotches. There can be no doubt that anthocyan production is strongly 

 influenced by sunlight and temperature, and possibly other environ- 

 mental factors, which differ in different localities. The deeper red spots 

 on 0. grandiflora in my cultures might be due to genotypic differences 

 between Gates's material of that species and mine, but it seems rather 

 more likely that they indicate a condition in my cultures favorable to 

 the intensification of the anthocyan colors. It is conceivable that a 

 form which does not possess red spots at all under one condition may be 

 strongly spotted under some other condition. This is directly illustrated 

 by the spotted plants themselves, for the spotting is an evanescent 

 character, which completely disappears as the rosettes grow older. The 

 occurrence of spotting in the young rosette-leaves in my cultures of 

 0. rubricalyx, does not necessarily prove, therefore, that my plants are 

 hybrid derivatives of 0. rubricalyx instead of that species itself, 

 although on certain grounds the assumption that they are hybrids may 

 seem to be the more tenable hypothesis. 



As the rubricalyx-pl&nts in this pedigree were of two types with 

 respect to the pigmentation of the stems, it was thought possible that 

 such splitting might also occur in the homozygous strain discovered by 

 Gates, but a letter from A. W. Button, Esq., Reading, England, informs 

 me that all of the 0. rubricalyx-plsmts from Gates's pure-breeding stock 

 have the brilliant red stems 1 . 



Oenothera rubricalyx x rubrinervis F^ 

 Pedigree Nos. 11410(1) x 1123(8)= 1232. 



The male parent was from a pure cross-bred strain of Oenothera 

 rubrinervis which had been fully controlled in my cultures in seven 

 consecutive generations, each of these ancestral generations having 

 resulted from a cross between two typical rubrinervis-specimens of as 

 widely separate relationship as my several cultures provided. All the 

 preceding generations had been uniformly typical 0. rubrinervis with 

 the exception of an extremely small percentage of aberrant individuals 

 which have appeared from time to time as characteristic mutants (?). 



Seeds from this cross yielded 205 individuals of which 8 died 

 unclassified. These were, like the progeny from the selfed 0. rubricalyx 



1 Seeds of this form are now being offered for sale by Sutton and Sons under the name 

 Oenothera Afterglow. ' 



