112 ORIGIN OF SPECIES 



Teady before the pollen of that flower is ready, so that these 

 so-named dichogamous plants have in fact separated sexes, 

 and must habitually be crossed. So it is with the reciprocally 

 dimorphic and trimorphic plants previously alluded to. How 

 strange are these facts ! How strange that the pollen and 

 stigmatic surface of the same flower, though placed so close 

 together, as if for the very purpose of self-fertilisation, 

 should be in so many cases mutually useless to each other? 

 How simply are these facts explained on the view of an oc- 

 casional cross with a distinct individual being advantageous 

 or indispensable ! 



If several varieties of the cabbage, radish, onion, and of 

 some other plants, be allowed to seed near each other, a large 

 majority of the seedlings thus raised turn out, as I have 

 found, 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 surrounded not only by its own six stamens 

 but by those of the many other flowers on the same plant; 

 and the pollen of each flower readily gets on its own stigma 

 without insect agency ; for I have found that plants carefully 

 protected from insects produce the full number of pods. 

 How, then, comes it that such a vast number of the seedlings 

 are mongrelized? It must arise from the pollen of a dis- 

 tinct variety having a prepotent effect over the flower's own 

 pollen ; and that this is part of the general law of good being 

 derived from the intercrossing of distinct individuals of the 

 same species. When distinct species are crossed the case is 

 reversed, for a plant's own pollen is almost always prepotent 

 over foreign pollen; but to this subject we shall return in a 

 future chapter. 



In the case of a large tree covered with innumerable 

 flowers, it may be objected that pollen could seldom be carried 

 from tree to tree, and at most only from flower to flower on 

 the sanre tree ; and flowers on the same tree can be consid- 

 ered as distinct individuals only in a limited sense. I believe 

 this objection to be valid, but that nature has largely pro- 

 vided against it by giving to trees a strong tendency to bear 

 flowers with separated sexes. When the sexes are separated, 



