1918} DEVRIES—MASS MUTATIONS 380 
two groups. Mutants were rare in these cultures. Among the 
laeta of the first cross an ochracea and a lorea were seen, and among 
its velutina a sulfurea. Moreover, a lorea appeared in the second 
generation of the /aeta of O. loreaXCockerelli. The table proves 
the complete analogy between the splitting phenomena of O. grandi- 
flora and O. Lamarckiana. 
TABLE III 
TWIN HYBRIDS OF O. grandiflora 
FIRsT GENERATION | SECOND GENERATION 
Percentage | Percentage Percentage Percentage 
Cross laeta velutina laeta velutina 
A. laeta and velutina 
O. biennisX grandiflora... .... sete 9° 10 uniform uniform 
O. syrticolaXgrandiflora*........ 47 53 . . 
O. syrticolaXgrandiflora.......... 42 58 > " 
O. suaveol grandiflora........ 61 21 PTS RS Si Cae 
‘ ‘ t 
O. CockerelliX grandiflora. ....... 33 67 ee a 
O. CockerelliX grandiflora... ...... 28 72 EOI ate c 
O. grandiflora Cockerelli........ 52 Fe ecwtae 
: 6 laet . 
{). loves % Cockérelli 3.50250, 60 40 7 io ane Te 
. lorea X Cocker oh. 40 Oe Apa uate s a ee aeehes 
O. grandiflora Chicago ......... 70 30 uniform uniform 
B. densa and laxa 
densa | laxa | densa | laxa 
0. Chicago grandiflora.......... 83 17 uniform uniform 
O. Chicago X grandiflora aie eres 75 25 : 
* The third generation continued uniform. 
O. biennis X grandiflora.—I made this cross in 1914 and culti- 
vated the first generation in 1915. It embraced 60 plants, almost 
all of which flowered in July and August. In the beginning of the 
flowering period I noticed the presence of two distinct types. The 
uppermost leaf beneath the spike was broad in /aela (3X10 cm.) 
and narrow in velutina (27 cm.), as were also the leaves and bracts. 
The color was yellowish and pale in the first, but less so in the 
