— 236 — 
This experiment was made in 1903 and was carried out in 
the following way: 
Some newly opened flower-heads of the same clump of H. 
pilosella which was used in castration experiment Ser. I4, and 
Ser. Ilı, were selected. Flower-heads of H. aurantiacum taken 
from the Danish Quarter of the Botanical Garden (Ser. I1 and 2), 
were passed accross the heads of H. pilosella in such a way that 
the aurantiacum-pollen, which was present in large quantity, 
could be cought by the papille of the stigmas. Afterwards the 
heads (with small labels) were left to ripen. The crossing was 
made in July and the ripe seeds were collected in August; next 
year (1904) they were sown in baked soil the 1st of May, germinated 
the 25th of May and were planted out in September; there were 
then 19 plants, which flowered for the first time, very sparingly, 
in October. It then appeared that, while the 18 specimens were 
true H. pilosella, the 19th was a hybrid, as will be seen from the 
fig. 7 on the Plate, which is a painting of the first flowering- 
scape. In June of 1905 the plant flowered again and continued so 
most of the summer. On June 7!h three heads were castrated, but 
they did not develop any ripe fruit; the same negative result came 
from a new castration of 4 heads in September. The intact heads 
gave mostly empty fruits, but also a few ones, which have germi- 
nated in September of 1905 and which (summer of 1906) are now 
planted out. Five specimens of this offspring have flowered now 
and are very remarkable being not like each other, some nearer 
Pilosella than the parent plant. There is the chance that the 
flowers of the hybrid may have been fertilisated by another plant, 
because the fruits have been taken from heads which not have 
been isolated under glass. 
The primary hybrid is still alive and flowers in this summer; 
of the pure pilosella-offspring one plant is kept back, while the 
others have been thrown away. 
The most important characters of the hybrid compared with 
those of the parents are to been seen from the scheme on p. 237. 
The explanation of this experiment is not easy to give; the 
fact is, that the same plants of H. aurantiacum and H. pilosella 
which, as proved by the castration experiments, produce apogamic 
seeds, are able to cross among themselves, forming a hybrid of 
ordinary, nearly intermediate aspect; the hybrid has a very reduced 
power of setting fruit and has hitherto not given any apogamic seed. 
