122 ON THE INTEK CROSSING [Chap. IV. 



pollen and stigraatic 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 facte explained 

 on the view of an occasional cross with a distinct indi- 

 vidual 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 seed- 

 ling 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 prod uce 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 distinct 



riety having a prepotent effect over the flower's own 

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

 beino* derived from the intercrossing of distinct indi- 

 viduals 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 same tree ; and flowers on the same tree 

 can be considered as distinct individuals only in a limited 



