22 



HYBRIDIZING. 



form of individual flowers, or greater pro- 

 lificacy, and improved arrangement, as re- 

 gards their collective production. Modifi- 

 cations and blending of colour, which are 

 also sometimes aimed at, seem to be the 

 most paltry changes (in a general sense), of 

 any that are attempted. These changes 

 affect appearance ; but among fruit and 



vegetables the changes to be effected should 



1 • J 



be confined more to productiveness and qua- 

 lity than to appearance. Thus the increase 

 of size, together with the improvement or 

 modification of the sensible qualities, are 

 the main objects to be sought, followed by 

 such qualities of general application as 

 greater hardiness, precocity, tardily, or pro- 

 ductiveness. In timber trees the produc- 

 tion of greater bulk is the first object, and 

 then the rendering of this bulk at least of 

 equal, if not superior, strength, toughness, 

 compactness, or whatever peculiar property 

 individual kinds may be prized for. 



It has been thought that a law very simi- 

 lar to that which obtains among animals 

 also regulates the production and fertility 

 of mule plants ; and so far as observations 

 have been made and recorded, this seems, 

 as a general rule,* to be near the truth. 

 Thus two distinct species of the same ge- 

 nus of plants will, in many cases, produce 

 an intermediate offspring, perfect as far as 

 regards the exercise of vital functions, but 

 defective as regards the power of perpetu- 

 ating itself by a seminal process. Even 

 when in the first generation this sterility is 

 not apparent, it becomes so in the second, 

 and less commonly in tne third or in the 

 fourth generation. Such mules may, how- 

 ever, be rendered fertile by the application 

 of the pollen of either parent, the charac- 

 ters of which then become assumed by the 

 offspring ; in other words, the hybrid form 

 reverts to that of one of its parents. Plants, 

 however, appear to possess this property of 

 admitting of hybridization far more gene- 

 rally than animals ; for while animal mules 

 are comparatively rare, there is scarcely 

 any family of plants that will not admit of 

 being hybridized with due care and atten- 

 tion. It is, however, only between species 

 in which the degree of relationship is some- 



•Much of what may militate against lliis opinion may pro- 

 bab y be referred lo some defeel in tlie present means and 

 mode o( constructing and distinguishing different genera. 



what close that this intercourse is effected ; 

 and as a rule, those plants which accord 

 most fully in general structure and consti- 

 tution will most readily admit of artificial 

 union. Species that are very dissimilar 

 appear to have some natural obstacle which 

 prevents mutual fertilization, and this ob- 

 stacle becomes insurmountable in the case 

 of very different genera. No such thing 

 as the intermixture of roses and black cur- 

 rants, and the consequent production of 

 " black roses," of which we do sometimes 

 hear, can therefore possibly take place. 

 There are some few recorded instances of 

 mules between different genera, but in 

 these cases a certain degree of relationship 

 existed, and the productions were both. 

 sickly and short-lived. Thus Gasrtner is 

 said to have obtained such hybrids, or bige- 

 ners, as they are termed, between daturas 

 and henbane and tobacco, (all solanaceous 

 plants,) and between the poppy and horn 

 poppy, (both of the same natural order.) 

 Weigman was successful in mixing lentils 

 and vetches, (both leguminous.) Mr. Knight 

 is recorded to have crossed the almond with 

 the peach, (both rosaceous.) Ktilreuter is 

 recorded to have effected a similar union 

 between different malvaceous plants ; and 

 Sageret obtained a cross between the cab- 

 bage and horseradish, which are both cru- 

 ciferous plants. The Dean of Manchester, 

 who has given much attention to the sub- 

 ject, and by far the best account of mule 

 plants which has appeared, regards these 

 and other like statements as erroneous, or 

 at least doubtful, and supports this opinion 

 by ihe fact that, in this country, where the 

 passion for horticulture is very great, and 

 the muling of plants has been carried to a 

 great extent, there is no undoubted instance 

 of a mule between distinct genera. On the 

 other hand, there are many cases recorded 

 of closely allied species refusing to inter- 

 mix, Mr. Knight could not succeed in ef- 

 fecting a cross between the common and 

 Morello cherries ; and Dr. Lindley men- 

 tions his own vain endeavors to cross the 

 gooseberry and the currant. Such plants 

 as the apple and the pear, the raspberry 

 and the blackberry, though very closely 

 related, have not been known to intermix. 

 Wild hybrid varieties occur but seldom ; 



