1918] DEVRIES—MASS MUTATIONS 391 
In this first generation the differences were observed in the 
beginning of June, since the velutina were small plants with narrow 
kennel-shaped leaves, whereas the Jaeta were stout and had broad, 
flat leaves. These differences increased in July and August during 
the flowering period. The Jaeta were grass-green, but the velutina 
more gray; these latter had broad flower buds (7X22 mm. as 
compared with 5 X27 mm. in the /aefa). The petals were somewhat 
larger (3 cm.) in the Jaeta and smaller (2 cm.) in the velutina. The 
fruits were thin in the first named hybrid, but conical in the other. 
O. suaveolens XO. grandiflora.—I made this cross in 1915 and 
cultivated only the first generation. It consisted of 61 per cent 
laeta, 21 per cent velutina, and 18 per cent of a third type, among 
69 specimens, most of which have flowered. The three types were 
discerned in June and evident in July and August, although the 
differences between Jaeta and velutina were only small. Height of 
laeta in July 60-80 cm., of velutina 40-60 cm., midveins reddish in 
the first, white in the second. Leaves 3X10 cm. as compared with 
3X15 cm. in July, and 3.511 cm. as compared with 2X9 cm. in 
August. The flower buds and flowers showed only small differences. 
The remaining 18 per cent were set off sharply against the rest, and 
this from the very beginning. They had the pale color, broad 
leaves, and low stature of the corresponding mutants of both par- 
ents, O. suaveolens lutescens and O. grandiflora ochracea. They must 
evidently be ascribed to the same mutability. Their flowers were 
intermediate between those of the parents. It should be noticed 
that this is the only case among all the experiments given in table 
III in which a third type showed itself besides the ordinary twins, 
apart from stray mutants.’ This shows that a special feature of 
mutability in O. suaveolens must be responsible for it. 
O. Cockerelli XO. grandiflora.—Since O. Cockerelli is an isogamic 
species, the results of both the reciprocal crosses are the same, with 
the exception that the hybrids of the cross just named are liable to 
beé more or less pale in their foliage, as is so often the case in crosses 
in which O. Cockerelli is the female parent, as for example in 
O. Cockerelli X suaveolens. In our case it is the Jaeta which show 
3 Mutants of the ochracea type were seen among the Jaeta of the second generation 
from 0. grandiflora X Chicago; see later. 
