OENOTHERA GRAND1FLORA AIT. 215 



The differences were evident by May, since the leaves were broad 

 and clear green in the laeta, but narrower and darker in the velutina. 

 The velutina were quite uniform, but among both groups of laeta 

 some specimens showed the broad leaves, pale color, and low stature 

 of the mut. ochracea (7 and 12 specimens). The two main types 

 were both intermediate between their parents and much resembled 

 the corresponding twins of 0. Lamarckiana x Chicago. Leaves of 

 the stem of laeta were pale green and broad (4 x 14 cm.); those 

 of velutina dark green and narrow (2.5 x 12 cm.). Flower buds 

 were shorter and thicker in velutina than in laeta. The flowers them- 

 selves and the fruits were alike in the two twins. 



0. biennis Chicago x 0. grandiflora gives twins which resemble 

 those of 0. biennis Chicago x 0. Lamarckiana so closely that there 

 can be no hesitation in identifying them. I made the cross in 1913 

 on two specimens of the female parent, fertilizing them each with 

 the pollen of one grandiflora, but cultivated one offspring in 1914 

 and 1915, the other in 1915 and 1916, so that in 1915 I had a first 

 and a second generation on the same bed. The results were sensibly 

 the same, as may be seen in table 1 1 1. The leaves of the densa were 

 clearly broader than those of the laxa, especially in July and August, 

 when they flowered. In the densa the foliage was more dense and 

 the plants more richly branched but lower of stature, and more 

 like the female parent of the cross. The size of my cultures was 

 70 and 40, mostly flowering plants in the first generations, 60 for 

 each of the second generations of laxa, and 70 for each of those of 

 ■densa, making together 370 specimens. The differentiating characters 

 of the first generation were repeated in the uniform lots of the 

 second, where they proved to be clear and sharp. 



0. grandiflora ochracea x 0. Cockerelli. — Since the mass mutant 

 ochracea behaves differently from mut. lorea in so many respects, 

 I have studied its behavoir in this cross and the reciprocal one, in 

 order to see whether the splitting into laeta and velutina would be 

 repeated or not. I did not find it. Both crosses were made in 1915. 

 In 1916 their progeny embraced 60 and 37 specimens. This latter 

 number was small, because this reciprocal cross produced numerous 

 yellow seedlings, most of which were pale green and did not succeed 

 in developing their first leaves. Only 43 survived in the seedpan, 

 and among these 6 proved still too weak for a normal growth. It 

 is the same phenomenon often seen among the hybrids of 0. Cocke- 

 relli with other pollen. The culture retained some degree of paleness 

 during almost the whole summer. Apart from this, the hybrids 



