Analogy between Plants and Animals. 417 



Plants agree with animals in having a sexual system ; but they 

 differ from animals in having for the most part both sexes in the 

 same individual. In the improvement of plants, as in the im- 

 provement of animals, the sexual system is a powerful agent; 

 and what is called cross-breeding is employed with as great ad- 

 vantage in the vegetable as in the animal kingdom. It is re- 

 markable, that the general laws and results by which the process 

 of cross-breeding in both kingdoms is regulated are the same : 

 the two parents must be two varieties of the same species, and 

 their qualities may be different, but must not be opposite : the 

 preponderating influence, in point of character, is also with the 

 male, and in point of bulk and hardiness with the female, as it 

 is in animals. Many of the finest varieties of fruits, culinary 

 vegetables, cereal grains, and grasses, have been produced by 

 cross- breed in a;. When cross-breeding is effected between what 

 are considered different species, the offspring is a mule, or hy- 

 brid ; is incapable of maturing seeds ; and generally, in the 

 course of a few years, degenerates, or reverts to its original pa- 

 rentage. The purple laburnum, which was raised from a seed 

 of the common laburnum, fertilised by Cytisus purpureus, is an 

 example of a true hybrid. The flowers partake of the colour 

 of that of both parents ; and the plant, for two or three years, 

 produced only flowers of this kind, which were never succeeded 

 by seeds : but in the sixth year, in some plants, and seventh 

 and eighth in others, branches of Cytisus purpiireus were pro- 

 duced on some parts of the tree, and branches of the common 

 yellow laburnum on others, the latter bearing seed. (See Gard. 

 Mag., vol. xii. p. 225. ; and Arb. Brit., p. 590.) It thus appears 

 that a true mule, or hybrid, can with difficulty be propagated, 

 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 con- 

 sidered mules, may not be so ; and may, consequently, prove 

 permanent and improved varieties. Some mules, also, such as 

 that between the sweetwilliam and the common pink, are much 

 less liable to degenerate than others. As some of the most 

 beautiful and useful plants in cultivation are cross-bi-ed varie- 

 ties, or mules, the subject well deserves the attention of the 

 amateur, who will find it a source of useful amusement and 

 recreation. 



Plants agree with animals in the offspring, when it is raised 

 from seed, bearing a general resemblance to the parent ; but 

 as, in every family, the children of the same parent differ indi- 

 vidually in features, temper, disposition, &c., so, among seedling 

 plants from the same seed-pod, no two plants will be found 



Vol. XIV. — No. 102. e e 



