= tay Ty ee ae 
NOVEMBER, 1908. ] THE ORCHID REVIEW. 349 
and fell off like a faded flower. At the time I thought that perhaps the 
plants were not strong enough to bear fruit, or that I had not been successful 
in choosing the proper period for fertilising the flowers. Now I have found 
another explanation. On examining all the plants used, and comparing 
them with the notes I made about my experiment, I came upon the fact that 
only those plants refused to bear fruit which had been fertilised with the 
pollen of Odontoglossum Rossii. This pollen is evidently incapable of 
penetrating into the ovary of the Columbian Odontoglossums. The pollen 
of these on the other hand is quite applicable to the fertilisation of the 
flowers of O. Rossii. 
Similar observations have been made with other Orchids. I remember 
seeing a statement that negative results are invariably obtained with the 
pollen of Odontoglossum Uroskinneri, whilst as a seed-parent this species 
has an excellent reputation. Odontoglossum grande is supposed to give 
negative results either way with all other Odontoglossums excepting O. 
Insleayi and O. Schlieperianum. Last year I determined to try for myself, 
and I fertilised two flowers of O. grande with pollen of O. crispum. 
Two pods were formed which grew to a large size, but after about four 
months’ time both fell off in an unripe condition. 
On the other hand, I have just obtained ripe seed from Miltonia 
Warscewiczii crossed with Odontoglossum crispum. I do not know 
whether it will germinate, but if the result be negative I shall feel inclined 
to put it down to my want of skill as a raiser of Orchids from seed. 
OTTo N. WITT. 
Berlin. 
[We should be glad to have the experience of others on the subject, for 
we have previously heard of failures with O. Rossii, though we do not 
remember the precise details. Three hybrids of O. Rossii have been 
recorded, the other parents being O. X spectabile, O. cirrhosum and O. x 
Adrianz, but in each case O. Rossii appears to have been the seed parent. 
It is not an isolated case, for there are several hybrids which it is said 
cannot be obtained from the reverse cross, and in such cases it is clear that 
failure is due to some mechanical obstacle to fertilisation, for no physio- 
logical obstacle exists. Negative evidence is not always conclusive, but in 
some cases repeated trials have been made, with the same results. It would 
be interesting if the cause of failure could be ascertained. The ripe seed 
from Miltonia Warscewiczii mentioned should give seedlings of Odontonia 
Lairessez, although from the reverse cross. A few seeds might be sown in 
different places, and at different times, or some experienced friend might be 
induced to try a few seeds, for the old proverb about not putting all your 
eggs in one basket is always applicable.—ED.] 
