xxxvi. HYBRIDISING AND RAISING ORCHID SEEDLINGS. 
make considerable progress, and yet go off, if for any reason the ovules 
should fail to be fertilised. 
Causes OF FalLuRE.—The period required for the development of the 
pollen tubes and ovules varies considerably in different Orchids, and this 
may represent one of the causes of failure when very distinct species are 
intercrossed. When a species is fertilised with its own pollen all the forces 
at work are in complete harmony, but when the pollen is derived from a 
widely distinct species the rhythm may be completely upset. The pollen 
may be capable of causing the development of the ovary and ovules, and yet 
fail to effect fertilisation when the proper time comes. The pollen tubes 
from a very distinct species may mature too soon or too late. Or they may 
be too large to effect an entrance into the micropyle of the ovule of the other 
species. Again, they may sometimes fail to reach the necessary length, or 
there may be some other incompatibility or obstacle to their proper develop- 
ment in the new combination. There are good reasons for the belief that 
in most cases where the ovary develops as the result of pollination without 
fertilisation being subsequently effected that the difficulty is largely a 
mechanical one, and one of them is the fact that in many cases a few good 
seeds are produced. There is also the well-known fact that in the case of 
Cattleya crossed with Sophronitis, and of Brassavola crossed with Cattleya, 
the fertile seeds are only found at the apex of the capsule. Again, Cattleya 
can be crossed with Epidendrum, but the reverse cross fails, and the reason 
is believed to be that the pollen tubes of Cattleya, and similar large-flowered 
Orchids, are too large to enter the micropyle of the ovule. 
MATURING OF THE CapsuLE.—If the capsules survive the period just 
mentioned—technically they cannot be called seed-capsules until after the 
ovules are fertilised—they will probably mature and ripen. The period of 
maturing varies greatly in different Orchids, and to some extent also under 
varying conditions, but as this stage approaches it is advisable to watch for 
the first sign of splitting, otherwise some of the seed may be lost. If the 
capsule then appears mature it may be cut at once, or tied up securely in a 
piece of loose tissue paper for a few days, so asto allow the seeds time to 
mature fully. In practice it is a general custom to tie up the capsule when 
nearly mature to prevent loss of the seeds before splitting is noticed, also to 
prevent the seeds from falling and germinating where not wanted. 
GATHERING THE SEED.—When the capsule is cut it should be removed 
to a dry shed, and as soon as ready may be opened, or the seed removed by 
tapping the capsule gently over a piece of tissue paper. As soon as any 
seeds fall they should be examined with a good lens to see if they appear 
perfect. If they appear plump in the centre and diminish considerably 
towards the pointed ends, they may be considered good, but if they look like 
hairs or chaff, without any thickening in the middle they are generally bad, 
