KEPRODUCTIVB ORGANS OF PLANTS. 333 



the fact that in the latter both parents, are likely to pos- 

 sess by inheritance the same imperfections, which are 

 thus intensified in the progeny, while in cross-breeding 

 the parents more usually have different imperfections 

 which often, more or less, compensate each other in the 

 immediate descendants. 



Hybridizing. — As the sexual union of quite different 

 kinds of animals sometimes results in the birth of a 

 hybrid, so, among plants, the ovules of one kind (spe- 

 cies, or even genus) may be fertilized by the pollen of 

 another different kind, and the seed thus developed, in 

 its growth produces a hybrid plant. As in the animal, 

 so in the vegetable kingdom, the range within which 

 hybridization is possible appears to be very narrow. It 

 is only between rather closely allied plants that fecunda- 

 tion can take place, and the more close the resemblance 

 the more ready and fruitful the result. Wheat, rye, 

 and barley, in ordinary cultivation, show no tendency to 

 " mix ; " the pollen of one of these similar plants rarely 

 fertilizing* the ovules of the others. But external sim- 

 ilarity is no certain mark of capacity for hybridization. 

 The apple and pear have never yet been crossed, while 

 the almond and nectarine readily form hybrids. (Sachs. ) 



Hybrids are usually less productive of seeds than the 

 parent plants, and sometimes are entirely sterile, but, on 

 the other hand, they are often more vigorous in their 

 vegetative development — produce larger and more numer- 

 ous leaves, flowers, roots, and shoots, and are longer- 



*In the first edition was written, "being Incapable of fertilizing." 

 Tlie experiments of Mr. Carman have lately shown that wheat and 

 rye may be made to produce fertile hybrids. A beardless wheat was 

 fertilized by rye-pollen aridprodiiced nine seeds, eight of which were 

 fully fertile, one nearly stenle. The last yielded 20 heads, wli^ch bore 

 only a few grains. The plants from the nine fertile seeds were polli- 

 nated again with rye and produced but a few fertile seeds. A few 

 plants, seven-eighths rye, were finally produced, which were, however, 

 totally sterile. ■ Of the three-fourths cross, fertile progeny has been 

 raised for several years, and the characters of this genus-hybrid ap- 

 pear to be nearly fixed, though occasionaUy a sterile head appears. — 

 aural New Yorker, 1883, p. 644. 



