78 On the Intercrossing of Individuals. Chap, iv 



freely in my garden. In very many other cases, though there is no 

 special mechanical contrivance to prevent the stigma receiving 

 pollen from the same flower, yet, as Sprengel, and more recently 

 Hildebrand, and others, have 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 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 ex- 

 plained on the view of an occasional 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 mon- 

 grelized ? It must arise from the pollen of a distinct 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 same tree; and 

 flowers on the same tree can be considered as distinct individuals 

 only in a limited sense. I believe this objection to be valid, but 

 that nature has largely provided against it by giving to trees a 

 strong tendency to bear flowers with separated sexes. ° When the 

 sexes are separated, although the male and female flowers may be 

 produced on the same tree, pollen must be regularly carried from 



