132 REPRODUCTION IN PLANTS AND ANIMALS. 



is restricted to the nearly allied species of the same genera, 

 and in neither case is the hybrid capable of perpetuating 

 its kind, in animals, beyond a single generation, and in 

 plants, beyond the second or third. The hybrid vegetable 

 if reproduced from seed, either reverts back to the charac- 

 ter of one of its parents, or becomes sterile. 



Among the native plants of North America, hybrids are 

 not produced to that extent which we would be led to sup- 

 pose. The numerous pollen grains of different species 

 borne on the wandering winds from the male flowers of any 

 particular species of plant, are so exactly adapted to the 

 female flowers of the same species, that they become abor- 

 tive on the pistil of any other plant. Hybrids are there- 

 fore very rarely produced by wild plants, as the stigma of 

 any particlar species of plant is much more likely to attract 

 the pollen of its own stamens than that of other plants. The 

 species of the genus Verbascum, or shepherd's flannel, a 

 tall plant, very common along road-sides, with a leaf not 

 unlike a piece of flannel, and a spike of yellow flowers, 

 show a greater tendency to hybridize than almost any other 

 species. 



Hybrids are much more common among cultivated and 

 domesticated plants, than among wild ones. It is a fact 

 well known to cultivators of Ericas, Pelargoniums, Mesem- 

 bryanthemums, and Stapelias, in the green-house, that 

 when several species of any of these genera are grown to- 

 gether, and plants are raised from seed, they will frequently 

 turn out hybrids. 



It is the constant practice of gardeners to produce the 

 different varieties with which their green-houses are adorned, 

 by conveying the pollen from one plant with a corolla of a 

 certain color, to the pistils of another plant with a corolla of 

 a different hue. The seed thus generated will develop a 



