100 Neqatwe Correlation hi Oenothera ITjihruh 



absence of the chlurojjlasts. Numerous investigators have sliown tliut 

 the anthocyan pigments of many plants are determined in (juantity, 

 quality and distribution by normal Mendelian genes, but the studies 

 described in this paper, as well as those of Gates, strongly indicate that 

 in Oenothera the inheritance of the red-pigmentation is determined by 

 some other hereditary system, and the same inference may be drawn 

 from most of the other genetic phenomena thus far recorded for Oeno- 

 theia. Further experimentation must discover a mechanism adecpiate 

 for the interpretation of these genetic phenomena. Until that mechanism 

 is found it will be impossible to decide what constitutes a unit-character 

 in Oenothera, or to decide whether any paitieular genetic ditf'eieiitiation 

 represents a case of segregation, " fractionation," or some other method 

 of distribution (jf characters. 



Summary. 



An investigation of the genetic phenomena presented by Oenothera 

 ruhricaly.T Gates and its hybrids has shown that the bright red 

 hypanthia and cones of that .species are separable in inheritance from 

 the brilliant red stems with which, according to Gates's description, it 

 was always associated in his cultures. 



In the Fi hybrids from reciprocal crosses between this species and 

 0. ruhrinervis and 0. Lainarckiana a remarkable series of negative 

 correlations appear in the distribution of the red pigment, the brilliantlv 

 pigmented buds characteristic of 0. ruhrlady.r being invariably associated 

 with a low degi'ee of red-pigmentation in the stems and rosettes ; pink- 

 coned buds with green hypanthia, characteristic of 0. Lamarckiaiin, 

 being on the other hand, invariably associated with brilliant red stems, 

 while buds entirely free from anthocyan are associated with dull dark- 

 red stems. 



A self-fertilized plant of 0. ridmcalyx produced offspring having 

 rubrical yx-hwds and green buds in the ratio 10'7 : 1, all the green- 

 budded plants having Jitme^^a-stature and chai-acteristic dark-red stems. 

 One plant having r)/7wica?//;t-pigmentation was likewise of the dwarf 



typf- 



The ratio of ruhriculyx-hwAAeA plants to non-rubricalyx in the 

 crosses with nibrinervis was approximately 1:1, and in crosses with 

 Lamarckiana 2:1. 



By complicated auxiliaiy hypotheses these ratios could be explained 

 in accord with Mendelian inheritance, but the fjxct that Oenothera 

 apparently has a unique mechanism for the distribution of hereditary 



