CROSSING OR HYBRIDISING. 



315 



possesses the power of modifying the works of 

 nature, and rendering them better adapted to 

 his wants and wishes. What would our gardens 

 now he, were it not for the hundreds of beautiful 

 flowers produced by this means, as well as the 

 many superior fruits produced in a similar 

 manner ? The families of roses, azaleas, rhodo- 

 dendrons, pelargoniums, fuchsias, and hosts of 

 others, bear evidence of this ; while the improved 

 kinds of pears, apples, strawberries, peaches, 

 &c, give a still more conclusive corroboration. 

 By this process the races of fruits and of culi- 

 nary vegetables have been brought as near to 

 perfection as it is, perhaps, possible to bring 

 them ; and it is more than probable that wheat, 

 corn, barley, &c. are capable of being yet greatly 

 improved if sufficient pains were taken with 

 them. Nay, even the timber trees of our forests, 

 which are subject to the same laws, are capable 

 of a like improvement. 



The Laws of hybridisation, or cross-breeding. — 

 "The species to be experimented on must be 

 nearly related. The apple will not cross with 

 the pear, nor the gooseberry with the currant." 

 — Keith. 



M. Decandolle says, "that hybrids resemble the 

 female parent chiefly in the leaf and stem, and 

 the male parent chiefly in the flower and organs 

 of fructification." Professor Lindley reverses 

 this order, which has led Keith to remark that 

 the resemblance may have been found to be 

 sometimes the one way, and sometimes the 

 other. The Hon. and Rev. W. Herbert thinks, 

 from what he saw in Amaryllides, that in hybrids 

 the flowers and organs of reproduction partake 

 of the character of the female parent ; while the 

 foliage and habit, or the organs of vegetation, 

 resemble the male. "Hybrids may be fertilised, 

 however, by the pollen taken from one of the 

 parents, and then the offspring assumes the 

 character of that parent." — Balfour. 



Further, on this very interesting subject Dr 

 Lindley remarks, in "Theory of Horticulture," 

 that "if the pistil of one species be fertilised 

 by the pollen of another species, which may 

 take place in the same genus, or if two distinct 

 varieties of the same species be in like manner 

 intermixed, the seeds which result from the 

 operation will be intermediate between its pa- 

 rents, partaking of the qualities of both father 

 and mother. In the first case, the progeny is 

 hybrid, or mule ; in the second, it is simply 

 cross-bred. In general, cross-breeds are capable 

 of producing fertile seed, and thus of perpetuat- 

 ing one of the species from which they sprang. 

 Hybrids, on the contrary, are often sterile, and 

 therefore incapable of yielding seed. Reasoning 

 from a few facts, and from the analogy of the 

 higher orders in the animal kingdom, it has 

 been believed that all vegetable hybrids are 

 sterile ; and when sterility is not the conse- 

 quence of the intermixture of two species, it has 

 been thought that such species are not naturally 

 distinct, however different their appearance. 

 But facts prove that undoubted hybrids may be 

 fertile ; and when we consider that plants are 

 not analogous to the higher orders of animals, 

 but to the lowest, concerning whose habits we 

 know nothing whatever, it is obvious that no 



analogical inferences can be safely established." 

 — (Vide Mr Anderson's views at the end of the 

 article.) 



Duration of hybrids. — "Hybrids are fertile 

 only till the third or fourth generation, when 

 they revert ultimately to the type of one of the 

 parents." — Keith. " When cross-breeding is ef- 

 fected between what are considered different 

 species, the offspring is a mule, or hybrid, which, 

 in most cases, is incapable of maturing seeds, 

 and generally, in the course of a few years, de- 

 generates, or reverts to its original parentage. 

 There are, however, instances of mules, or true 

 hybrids, producing fertile seeds, from which 

 plants have been raised, partaking of all the 

 characters of the parent hybrid plant," as in the 

 case of some of the Cacti. — Sub. Hort. 



Uncertainty in 'propagating hybrids even other- 

 wise than by seed. — " It would appear, from the 

 case of the Cytisus adami, or purple laburnum, 

 that a true hybrid or mule cannot always be 

 propagated with certainty, even by portions of 

 the plant, or by what is called extension, since 

 it never can be certain whether the portion 

 taken off for propagation will produce the mule 

 or one of the parents. As it is uncertain what 

 are and what are not very distinct species, 

 many of the plants originated by cross-breeding, 

 and considered mules, may in reality not be so, 

 and may consequently prove permanent and 

 improved, varieties." — Idem. In this extraordi- 

 nary tree the foliage is sometimes that of the 

 common laburnum, sometimes of the purple 

 cytisus (C. purpureus), and sometimes interme- 

 diate between the two. The origin of this ano- 

 malous tree is not believed to have been from 

 seed produced by the ordinary process of cross- 

 breeding, but by some accidental mixture of the 

 cellular tissue. 



The difference between propagating by seed and 

 propagating by any other mode is very great. — 

 In propagating by seed, the species or variety 

 in the abstract is propagated ; while by all the 

 other modes practised by gardeners the species 

 or variety is continued without alteration in 

 character, by an extension of the parts of the 

 original tree or plant. Thus, a Hawthornden 

 apple of 1852 is not a new plant, but only a por- 

 tion of the original tree continued by the process 

 of extension, carrying with it its habits and pro- 

 perties. Were we to sow the seeds of variegated 

 plants, or of weeping oaks, ashes, or elms, few 

 of the progeny, if any," taking it as a general 

 rule, would exhibit the variegated or pendulous 

 characters of their parents ; and hence the neces- 

 sity of continuing these varieties by budding, 

 grafting, &c. On the same principle, were we 

 to sow the seeds of any of our best apples, pears, 

 plums, &c, the chances of obtaining from their 

 seeds improved varieties, or even such as are 

 equal to the parents, would be few indeed ; we, 

 therefore, are compelled to continue them by 

 other means than from seeds. There are, how- 

 ever, exceptions to this rule, as in the case of 

 the pendulous or weeping oak at Moccas Court, 

 many of the acorns of which, when sown, pro- 

 duce plants very similar to the original ; and we 

 recollect having pointed out to us by the Due 

 d'Aremberg a splendid purple or copper-coloured 



