24 



DE. B. E. GATES— CONTEIBUTION TO A 



prove to be one of tlie salient features of heredity in Oenothera, and may account for 

 some of the almost hafflingly difficult phenomena to he observed among these forms. 



The following represents the history of one such O. LamarcUana race. It was derived 

 from a single individual which appeared from an unknown source in the back-yard of a 



citizen of St. Louis. Mo., wher 



no Oenotheras had previously been 



that 



origm cannot even be conjectured. From pure seeds of this individual I grew in 1910 a 

 uniform offspring of 38 plants. Pig. 9 shows the range of variation of the seedlings, 

 which was not very great. The close similarity to DeVries's race of O. LamarcUana (at 

 a somewhat younger stage) is shown by comparing PL 1. fig. 1. Three plants of the Pj 

 were self -pollinated as parents for the next generation, and yielded respectively 62, 29, 

 and 41 plants, making a total of 132 plants in the F^. PI. 1. figs. 10 and 11 show a 



figs. 5 and 8 



The 



typical rosette and adult plant for comparison with PI. 1. 

 rosette-leaves of this race are crinkled similarly to the plants of DeVries's race, but they 

 have decidedly broader leaves and the latter are conspicuously larger, so that the rosettes 

 reach a much greater diameter. The individual leaves of the mature rosettes also show 



wider fluctuation than in BeVries 

 variable than in DeVries's form. 



Th 



. The stem-leaves of this race are also much more 

 same individual may bear leaves ranging all the 



way from ovate, tapering at both ends, and petiolate (thus resembling O. grandiflora) to 



nearly so, with broad and aurate base (as is usual in O. LamarcUana). These 



leaf types do not always foi 



definite transition 



but one type may be found 



chiefly on the main stem and the other on a side branch. Both rosette- and stem-lea\ 

 are, on the average, somewhat more crinkled than in DeVries's race, and the buds bear 

 fewer long hairs. On the whole, the fluctuating variabiHty of this race is decidedly 



greater than in the O. LamarcUana of DeVries's cultures 



This is, perhaps, due to the 



fact that continued inbreeding has decreased the range of ordinary variation in the latter 



race. 



Among the 132 individuals of this race in the Fs, all belonged to the parent type but 

 two plants which must be classed as mutants. One of these was a dwarf, corresponding to 

 hut not agreeing with 0. nanella, the other a narrower-leaved one, corresponding to 



This race of O. LamarcUana, therefore, is capable of producing aberrant 



not identical with, those described by DeVries: a fact of 



O. rubrinervis 



types analogous to, but 



derable interest. The following table summarizes these facts 



F 



38 plants. 



No. 3.5. 



No. 1.1. 



No. 2.2. 



Table II. 



F 



62 plants, 



29 



>» 



41 



79 



132 „ 



Mutants. 



1 narrow-leaved plant 

 1 dwarf plant. 



