No. 4.] CROSSING OF PLANTS. 4i 



the fruits. This simply means that it is difficult to fix hy- 

 brids so that they will come "true to seed," and makes 

 apparent the fact that if we desire hybrids we must expect 

 to propagate them by means of buds. And this, too, is a 

 point which appears to have been overlooked by those who 

 contend that hybridization must necessarily swamp all results 

 of natural selection ; for, as comparatively few plants prop- 

 agate naturally by means of buds, whatever hybrids might 

 have appeared would have been speedily lost, and all the 

 more, also, because, by the terms of their reasoning, the 

 hybrids would cross with other and dissimilar forms, and 

 therefore lose their identity as intermediates. Or, starting 

 with the assumption that hybrids are intermediates, and 

 would therefore obliterate specific types, we must conclude 

 that they should have some marked degree of stability ; but, 

 as all hybrids tend to break up when propagated by seeds, 

 it must follow 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, therefore, pronounced intercrossing would have 

 obliterated the very organs upon which it depends, or have 

 destroyed itself. 



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

 reason why hybrids should not become stable through seed- 

 production by in-breeding, and I might be cited to the opin- 

 ion of Darwin and others that in-breeding tends to fix any 

 variety, whether it originates by crossing or other means. 

 And it is a fact that in-breeding 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 exper- 

 iments 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 in-breeding ; for 

 in-breeding without disastrous results 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 in-breeding. It some- 



