—— 
Dr Vries: ATAVISTIC VARIATION IN OENOTHERA 81 
root leaves. In my cultures these side-stems do not ordinarily 
become tall enough to bear flowers. But by cutting out the main 
stem at an early period I could induce the others to a more vigor- 
ous growth. I repeatedly made this experiment; but will only 
cite here observations made on a single plant in the summer of 
1901, grown from seed of a purely cruciate parent. It made six 
side-stems, out of which three bore only atavistic or broad-petalled 
flowers. The three other stems likewise produced obcordate 
petals, but not exclusively, bearing on one side of the spike flowers 
with the narrow and variable petals of the above-named intermedi- 
ate types. 
Such cases prove that the atavistic individuals are not, or at 
least are not always, so constant as could be deduced from the 
figures above given. Analogous instances of sectorial variation, 
one sector of the spike bearing other flowers than the remaining 
sectors, were from time to time observed on atavistic individuals 
and also on intermediate ones, the sport giving flowers with ob- 
cordate petals. As yet I have found no such sports on plants of 
the purely cruciate type nor purely cruciate flowers on those of the 
two other types. But I have no doubt that this is only due to the 
small extent of my cultures. 
PEDI .REE OF 
Oenothera cructata varia 
Number of individuals of each type: 
Conte Intermediate. Atavistic. 
44 : : 
4th generation | —H- fe 
Igor, 39 : “ 
’ 45 
5th generation. : 
net 
24 2 re 
1900, 4th generation. | ore 
| 
22 o 8 
1899. 3d generation. 30 ad 4 o 58 
— 
(No. 1.) (No. 2.) (No. 3.) | 
1898, 2d generation, <a —— 5 2 
4 ay 
VY 
1897. Ist generation. I 
