100 Negative Correlation in Oenothera Hybrids 



absence of the chloroplasts. Numerous investigators have shown that 

 the anthocyan pigments of many plants are determined in quantity, 

 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 -pigment at ion 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- 

 thera. Further experimentation must discover a mechanism adequate 

 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 particular genetic differentiation 

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

 of distribution of characters. 



. SUMMARY. 



An investigation of the genetic phenomena presented by Oenothera 

 rubricalyx 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 F l hybrids from reciprocal crosses between this species and 

 0. rubrinervis and 0. Lamarckiana a remarkable series of negative 

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

 pigmented buds characteristic of 0. rubricalyx being invariably associated 

 with a low degree of red-pigmentation in the stems and rosettes ; pink- 

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

 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. rubricalyx produced offspring having 

 rubricalyx-buds and green buds in the ratio 10*7 : 1, all the green- 

 budded plants having nanella-st&ture and characteristic dark-red stems. 

 One plant having rubricalyx-pigment&iioii was likewise of the dwarf 

 type. 



The ratio of rubricalyx-budded plants to non-rubricalyx in the 

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

 Lamarckiana 2:1. 



By complicated auxiliary hypotheses these ratios could be explained 

 in accord with Mendelian inheritance, but the fact that Oenothera 

 apparently has a unique mechanism for the distribution of hereditary 



