186 BOTANICAL GAZETTE [MARCH 
them grow separately. The experiment succeeds easily if the 
rosettes have produced one or two roots of their own, however 
young and slender these may be. O. biennis nanella shows the 
same character, and in August I succeeded in isolating from my 
8 pure line dwarfs 8 rosettes, all of which have since developed 
into healthy young plants with some long and narrow leaves, 
followed by almost sessile ones, quite different from the rosettes 
of normal O. biennis. 
Moreover, two nanella mutants occurred in the cultures of 
O. biennis sulfurea which I shall have to describe later. These 
cultures were grown from self-pollinated seeds of the four sulfurea 
mutants of Stomps (1913), and embraced over r1ooo flowering 
individuals, the flowers of which were pale yellow without exception. 
Two of these plants proved to be dwarfs and were transplanted into 
my experimental garden. Both of them have flowered with pale 
flowers, have been self-pollinated, and yielded a sufficient harvest 
of seeds. The coefficient of mutation in this race was therefore 
0.2 per cent, which does not differ essentially from the first instance 
(o.1 per cent). These dwarfs are the founders of a new race, 
O. biennis sulfurea nanella, which I propose to cultivate next year. 
Its pedigree name would be O. biennis mut. (1913) sulfurea mut. 
(1914) nanella. It is a double mutant, such as are quite common 
in horticulture, and shows the way in which wild species would 
have to be analyzed. . 
I used the pollen of the O. biennis nanella of Stomps, in 1913; 
for two crosses, which may be briefly mentioned here. In the first 
place, I fertilized castrated flowers of the pure line of O. biennis. — 
The pollen was not abundant, and I got only 15 good seeds, all of 
which have germinated and become stout flowering plants. They 
differed from normal O. biennis in no respect and at no moment 
during their development. Their self-pollinated seeds will have 
to be sown next year. In the'second place, I pollinated O. Lamarck- 
tana with the pollen of O. biennis nanella. From this cross I had 
a culture of 55 individuals, all of which have flowered. One of 
them proved to be a Jata mutant, having besides the Jata marks the 
same characters as its sisters. These were all alike and in no way 
different from the ordinary and well known type of O. Lamarck- 
