Chap. IV. 
OF INTEKCKOSSING. 
99 
be no special mechanical contrivance to prevent the 
stigma of a flower receiving its own pollen, yet, as 
0. C. Sprengel has shown, and as I can confirm, either the 
anthers burst before the stigma is ready for fertilisation, 
or the stigma is ready before the pollen of that flower 
is ready, so that these plants have in fact separated 
sexes, and must habitually be crossed. How strange 
are these facts! How strange that the pollen and stig- 
matic surface of the same flower, though placed so close 
together, as if for the very purpose of self-fertilisation, 
should in so many cases be mutually useless to each 
other! How simply are these facts explained on the 
view of an occasional cross with a distinct individual 
being advantageous or indispensable I 
If several varieties of the cabbage, radish, onion, and 
of some other plants, be allowed to seed near each other, 
a large majority, as I have found, of the seedlings thus 
raised will turn out mongrels: for instance, I raised 233 
seedling cabbages from some plants of different varieties 
growing near each other, and of these only 78 were true 
to their kind, and some even of these were not perfectly 
true. Yet the pistil of each cabbage-flower is sur¬ 
rounded not only by its own six stamens, but by those 
of the many other flowers on the same plant. How, 
then, comes it that such a vast number of the seedlings 
are mongrelized ? I suspect that it must arise from the 
pollen of a distinct variety having a prepotent effect 
over a flower’s own pollen; and that this is part of 
the general law of good being derived from the inter¬ 
crossing of distinct individuals of the same species. 
When distinct species are crossed the case is directly 
the reverse, for a plant’s own pollen is always prepotent 
over foreign pollen; but to this subject we shall return 
in a future chapter. 
In the case of a gigantic tree covered with innume- 
F 2 
