126 Plant-Breeding 



upon what is perhaps the most important practical con- 

 sideration in hybridization, the fact that the greater 

 number of the best hybrids in cultivation are increased 

 by bud-propagation, as cuttings, layers, suckers, buds, or 

 grafts. In fact, there are very few examples in this country 

 of good undoubted hybrids which are propagated with 

 practical certainty by means of seeds. The genera in 

 which the hybrids are most common are those in which 

 bud-propagation is the rule ; as begonia, pelargonium, 

 orchids, gladiolus, rhododendron, roses, cannas, and the 

 fruits. This simply means that it is difficult to fix hybrids 

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

 the fact that if we desire named hybrids, we must expect 

 to propagate them by means of buds. 



This point appears to have been overlooked by those 

 who contend that hybridization must necessarily swamp 

 all results of natural selection; for, as comparatively 

 few plants propagate habitually by means of buds, 

 whatever hybrids might have appeared would have been 

 speedily lost, and all the more 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 if they are to swamp or 

 obliterate the characters of species; 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 



