NEW DIMORPHIC MUTANTS OF THE OENOTHERAS. 



91 



dense, and the flowers much stouter. Every evening 4 or 5 flowers 

 opened on the same spike, against 1 or 2 in ordinary cases. The 

 number of fruits on a spike was 60-80, whereas 40 fruits, as just 

 given, is a high value for an annual plant. All of these fruits were 

 self-pollinated in little bags, and yielded 1-1.3 cc. of seeds from 

 10 fruits, whereas the annuals give only 0.5-0.9 cc. of seeds in 

 10 fruits. We may summarize these details by saying that my 

 biennial specimens of 1914 were about twice as vigorous as the 

 very best of all my annual cultures. 



All the seeds were sown in boxes in 1915 and the seedlings 

 counted out, without being transplanted, in the stage correspond- 

 ing to fig. 1, when the differentiating marks were very sharp. The 

 three plants gave the results shown in table IV. 



Table IV. 



The remaining 4-7 and 3 per cent were mostly of the Lamarcki- 

 ana type, with some mutants belonging to albida, oblonga and 

 nanella. I had saved the fruits and their seeds in 7 or 8 groups, 

 beginning at the base of the spike, and sown the seeds separately. 

 But, just as in the previous case, there were no appreciable differ- 

 ences in the percentage figures between the higher and the lower 

 groups. 



The main result is that the percentage of specimens of the cana 

 type, which runs 15-60 per cent on annual individuals, may increase 

 to 93-97 per cent on very vigorous biennial plants. It is thus clearly 

 seen to be dependent upon the method of cultivation. Obviously 

 this rule may be applied to the percentages of 0. scintillans, as 

 previously discussed, and to those of 0. pallescens and the other 

 new dimorphic mutants to be described in this article. 



Oenothera Lamarckiana mut. pallescens (fig. 3). — Among all 

 the mutants which arose in my garden from 0. Lamarckiana, this 

 form most closely resembles the parent type. In early stages the 

 rosettes are the same, and in springtime, when still in the boxes, 

 I have not as yet succeeded in distinguishing them. It is not until 

 about 6 weeks after planting out on the beds that the differ 

 entiating marks begin to show (fig. 4). In the middle of June the 



