l8 MUTANTS AND HYBRIDS OF THE OENOTHERAS. 



maturity was comparatively small, and the possibility is not excluded 

 that a culture of several hundred plants might include still other 

 forms. In fact, the very differences between the results of the hybrid- 

 izations, as carried out in Amsterdam and New York, suggest that the 

 manner in which the various qualities in the two parents are grouped 

 in the progeny might be capable of a wide range of variation. Many 

 indications lead to the suggestion that the dominancy and prevalency, 

 latency, and recessivity of any character may be more or less influenced 

 by the conditions attendant upon the hybridization ; the operative fac- 

 tors might include individual qualities as well as external conditions. 

 In addition to the hybrid individuals several specimens of the pistil- 

 parent, lamarckiana, and one of its mutants appeared in the cultures, 

 indicating that self-fertilization was not entirely prevented. This 

 might be accounted for in two ways. Castration might not have been 

 performed early enough to prevent the action of pollen being scattered 

 from a bursting anther upon a mature stigma while the operation was 

 being performed. Then, again, the possibility was not wholly excluded 

 that pollen from the bursting anthers which fell upon the bracts 

 inclosed in the parchment bags might have been carried to the stigmas 

 by currents of air caused by the compression or expansion of the 

 parchment bags. At any rate, the appearance of individuals of the 

 pistil -parent type may be taken as presumptive evidence that such self- 

 pollination occurred by some method, although the appearance of 

 individuals of the parental type in hybrids is well known. 



(I) A type represented by individual No. 2.1 (PI. XIII, fig. i) 

 showed a rosette of deeply dull-green leaves, more or less crinkled 

 and irregular in form and margin. In all about twelve plants of this 

 type were seen, although but five reached a stage sufficiently advanced 

 to send up a central stem. The rosettes were sparse and the leaves 

 thick and fleshy, and almost glabrous, except that some were minutely 

 pubescent on the veins beneath. The leaves of the rosettes varied 

 from narrowly linear in the earlier stages to linear-lanceolate with 

 obtuse apices, and to oblong-spatulate, broadest above the middle, 

 and acutish in some individuals. The laminae were revolute and 

 irregularly denticulate and formed narrow wings nearly to the base of 

 the petioles. 



The main axis of the hybrid individuals reached a height of 15 

 or 20 cm., at which stage in the development elongation ceased and the 

 lateral branches became very active ; in some instances no noticeable 

 elongation of the main axis occurred. Branches of this were more 

 rounded in outline and bore leaves of a structure somewhat more 



