MUTANTS AND HYBRIDS OF THE OENOTHERAS. 27 



that the spread of foliar surfaces and the density of arrangement of 

 the leaves was similar to lamarckiana, while the form, incisions in the 

 margin, and arrangement at apices of branches were similar to biennis. 

 In the same manner the capsule was nearly glabrous, but was found 

 to be distinctly four-angled. 



A fourth type, No. 2. 2 7, bore flowers not easily distinguishable from 

 the pollen-parent, being capable of self-fertilization, but with the parts 

 of the flower of greater size. From the other parent the unequal growth 

 of the leaves, which results in the crinkling of the laminae is shown 

 with a modification which causes convexities and concavities. 



The symmetrical terminal rosettes are also a lamarckiana charac- 

 ter of the entire laminae. An analysis of the remaining characters show 

 that nearly all are combinations of parental qualities. Perhaps the 

 most remarkable feature of this type is the appearance of qualities 

 usually exhibited only by species allied to the parents and not by the 

 parents directly. Among these may be mentioned the zigzag forma- 

 tion of the stem and the red coloration of the shoot. 



In view of the above results it is evident that a repetition of 

 the crosses between the mutant derivatives of 0. lamarckiana and 0. 

 biennis would yield much of interest. De Vries has repeatedly called 

 attention to the fact that the prevalency of the parental types in crosses 

 of mutants with each other and with the parental form may be altered 

 by nutritive conditions, and it may well be supposed that a similar 

 state of affairs may be found to exist in the hybrid described above. 



It will be of interest to trace the dominancy of the separate charac- 

 ters of the two parents throughout the hybrid considered as a whole. 

 Of these the one that may be seen earliest in the development of the 

 plantlets is the density of the rosettes due to the rapidity with which 

 the leaves on the shortened internodes of the young stems appear, and 

 their duration. Every individual in the hybrid, without exception, 

 showed a heavy rosette composed of about 12 to 20 leaves, after the 

 manner of lamarckiana. Plantlets of biennis of a similar age never 

 bore more than half that number. The character in question depends 

 upon the activity of the internode ; the dominant character entails a 

 more rapid succession of development in these members, as no differ- 

 ence could be detected in the duration of the individual leaves. 

 While the character itself would be classed as meristic in its nature, 

 yet it is really seen to rest upon a real and constant physiological 

 quality. In addition to the rate of growth, it is not improbable that 

 the greater density of the dominant rosette may be due in part to the 

 development of a greater number of internodes before the elongated 

 flowering shoot is sent up. 



