394 BOTANICAL GAZETTE [MAY 
Leaves of the stem of /aeta were pale green and broad (4X14 cm.); 
those of velutina dark green and narrow (2.512 cm.). Flower 
buds were shorter and thicker in velutina than in laeta. The flowers 
themselves and the fruits were alike in the two twins. 
O. biennis Chicago XO. grandiflora gives twins which resemble 
those of-O. biennis ChicagoXO. 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 III. The leaves of the 
densa were clearly broader than those of the /axa, 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. 
O. grandiflora ochracea XO. Cockerelli.—Since the mass mutant 
ochracea behaves differently from mut. lorea in so many respects, 
I have studied its behavior in this cross and the reciprocal one, in 
order to see whether the splitting into Jaeta 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 O. Cockerelli with other pollen. The culture retained some degree 
of paleness during almost the whole summer. Apart from this, the 
hybrids of the two reciprocal crosses were the same and constituted 
one uniform lot. In June the absence of velutina was clear; the 
