ig8 
THE ORCHID WORLD. 
[June, 1913. 
THE PHYSIOLOGY OF FERTILISATION. 
THE experiment of placing more than 
one kmd of pollen on the stigma of 
an Orchid is not entirely a new one, it 
has been done on several occasions, but usually 
with disappointing results when the seedlings 
flowered. More recent experiments, however, 
have shown that some advantage may possibly 
accrue from the method, and this brief article 
IS intended to record a few facts and to open 
up the subject for further work by considering 
some of the problems as fully as present 
circumstances will allow. 
In the first place, it is necessary to obtain a 
clear comprehension of the essential organs of 
fertilisation, so far as they relate to the 
practical side of the question, and in terms 
which may be understood by those who are 
not skilled botanists. 
The pollen masses consist of many 
thousands of separate grains, and although 
extremely minute, each one is a thoroughly 
complete male organ capable of fertilising one 
of the ovules, or immature seeds, situated in the 
ovary, or seed-pod. The ovary contains many 
thousands of ovules, each one of which must, 
in the ordinary sequence of events, be fertilised 
by a pollen grain before it can become fertile 
or capable of germinating. 
Now from the writer's experience the 
general belief with Orchid growers is that by 
some mysterious process the act of placing the 
pollen on the stigma causes the seed pod to 
grow and, after a period of about twelve 
months, to be full of ripe seed. Hybridists 
must fully realise the fact that these pollen 
grains grow, and actually pass down the style, 
or column, and come in contact with the ovules. 
And, also, that each single grain of pollen is 
usually capable of fertilising one ovule, and 
not more. Thus we must imagine many 
thousands of separate pollen grains, or males, 
growing down the column with the express 
purpose of fertilising about as many thousands 
of ovules, or females. 
In the majority of flowers, other than 
Orchids, the pollen grains are in the form of 
fine dust, easily blown about by the wind, and 
thus brought in contact with the stigmas of 
other flowers, fertilisation being duly effected. 
The removal of the pollen from one Orchid 
flower to another is carried out by the aid of 
insects who, while searching for nectar and 
food in the flower, unconsciously remove the 
pollen masses, and these becoming affixed to 
their body are thus carried to the next flower 
visited. Therefore, it is easily seen why the 
pollen grains must be so sticky and connected, 
or packed up as it were ready for the insect 
to carry away. 
Another important point to realise is that 
cutting the pollen masses in pieces with a knife 
in no way interferes with their power, the 
operation merely lessens the number of grains 
in each portion, just in the same way that 
cutting a sack of wheat in half would lessen 
the number of grains in both halves, but no 
one would suggest that each separate grain is 
rendered worthless by so doing. 
In the plant's natural country we are not 
concerned so much with hybrids, but with 
species, and although it is not known for 
certain whether m any particular species the 
number of ovules is equalled by a similar 
number of pollen grains, we do know that the 
masses of pollen are suitable and readily 
accepted by the stigma of the flower. But in 
the making of a hybrid it is sometimes found 
that the pollen masses are rejected. The side 
wings of the column close over the stigma and, 
instead of safely enclosing the precious 
substance, they, by some means or other, find 
their way beneath the pollen masses and 
practically remove them from the flower. 
From this action it is reasonable to assume 
that the number or size of the pollen grains 
may be unsuitable to the female organ, and 
proof of this theory lies in the fact that success 
has been achieved whenever a portion only of 
the pollen mass has been used. 
It is quite possible for several different 
hybrids to be produced from the same seed 
pod. In fact, there is no reason, theoretically, 
why as many different hybrids should not be 
produced as there are various kinds of pollen 
