18 The Rural Library. 



other end to their having been differentiated in too great a degree, or in some 

 peculiar manner." 



The difficulties in the way of successful results through hybridization 

 are, therefore, these : The difficulty of effecting the cross, infertility, insta- 

 bility, variability, and often weakness and monstrosity of the hybrids, and 

 the absolute impossibility of predicting results. The advantage to be 

 derived from a successful hybridization is the securing of a new variety 

 which shall combine in some measure the most desirable features of both 

 parents ; and this advantage is often of so great moment that it is worth 

 while to make repeated efforts and to overlook numerous failures. From 

 these theoretical considerations it is apparent that hybridization is essentially 

 an empirical subject, and the results are such as fall under the common 

 denomination of chance. And as it does not rest upon any legitimate func- 

 tion in nature, we can understand that it will always be difficult to codify 

 laws upon it. 



Among the various characters of hybrid offspring, I presume that the most 

 prejudicial one is their instability, their tendency still to vary into new forms 

 or to return to one or the other parent in succeeding generations. It is diffi- 

 cult to fix any particular form which we may secure in the first generation 

 of hybrids. At the outset we notice that this discouraging feature is mani- 

 fested entirely through the medium of reproduction ; and we thereby come upon 

 what is perhaps the most important practical consideration in hybridization, 

 the fact that the great majority of the best hybrids in cultivation are in- 

 creased by bud-propagation, as cuttings, layers, suckers, buds or grafts. In 

 fact, I recall very few instances in this country of good undoubted hybrids 

 which are propagated with practical certainty by means of seeds. You will 

 recall that the genera in which hybrids are most common are those in which 

 bud-propagation is the rule, as begonia, pelargonium, fuchsia, gladiolus, 

 rhododendron, roses, 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 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 propagate 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 hy- 

 brids 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 



