Cross- Breeding and Hybridizing. 19 



that bud-propagation would become more and more common, and this is 

 associated in nature with decreased seed-production. Now seed-production 

 is the legitimate function of flowers, and we must concede that as seed- 

 production decreased floriferousness must have decreased, and, that, there- 

 fore, pronounced intercrossing would have obliterated the very organs upon 

 which it depends, or have destroyed itself I 



But I may be met by the objection that there is no inherent reason why 

 hybrids should not become stable through seed-production by inbreeding, 

 and I might be cited to the opinion of Darwin and- others that inbreeding 

 tends to fix any variety whether it originated by crossing or other means. 

 And it is a fact that inbreeding tends to fix varieties, within certain limits, 

 but those limits are often overpassed in the case of very pronounced crosses, 

 whether cross-breeds or true hybrids. And if it is true, as all observation 

 and experiment show, that sexual or reproductive powers of crosses are 

 weakened as the cross becomes more violent, we should expect less and less 

 possibility of successful inbreeding, for inbreeding without disastrous re- 

 sults is possible only with comparatively strong reproductive powers. As a 

 matter of fact, it is found in practice that it is exceedingly difficult to fix- 

 pronounced hybrids by means of inbreeding. It sometimes happens, too, 

 that the hybrid individual which we wish to perpetuate maybe infertile with 

 itself, as I have often found in the case of squashes. It is often advised 

 that we cross the hybrid individual which we wish to fix with another like 

 individual, or with one of its parents. These results are often successful, 

 but of tener they are not . In the first place it often happens that the hybrid 

 individuals may be so diverse that no two of them are alike ; this has been 

 my experience in many crosses. And again, crossing with a parent may draw 

 the hybrid back again to the parental form. So long ago as last century 

 Kelreuter proved this fact upon nicotiana and dianthus. A hybrid between 

 Nicotiana rustica and N. paniculata was crossed with N. $aniculata 

 until it was indistinguishable from it ; and it was then crossed with 

 N. rustica until it became indistinguishable from that parent. Yet there is 

 no other way of fixing a hybrid to be propagated by seeds than by inbreed- 

 ing, so far as I know. Fortunately, it occasionally happens that a hybrid is 

 stable and therefore needs no fixing. 



In this connection I may cite some of my own experience in crossing egg- 

 plants and squashes ; for although the products were not true hybrids in the 

 strict interpretation of the word, many of them were hybrids to all intents 

 and purposes because made between very unlike varieties, and they will 

 serve to illustrate the difficulties of which I speak. Offspring of egg-plant 

 crosses were grown in 1890, and upon some of the most promising plants 

 some flowers were self-pollinated. But these self-pollinated seeds gave just 



