68 VITAL ACTIONS. 



vidual peculiarities ; the seed of a Green Gage Plum, 

 for instance, will not, with any certainty, produce a 

 plant having the sweet green fruit of that variety, 

 but it may produce a plum whose fruit is red and 

 acid. All that the seed will certainly do is to pro- 

 duce a new individual of the plum species ; the pecu- 

 liarities of individuals are perpetuated by other 

 means, and especially by leaf-buds. (See Book II.) 



88. 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 seed which 

 results from the operation will be intermediate be- 

 tween its parents, 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 crossbred. 



89. In general, crossbreds are capable of producing 

 fertile seed, and thus of perpetuating one of the spe- 

 cies from which they sprang. Hybrids, on the con- 

 trary, are often sterile, and therefore incapable of 

 yielding seed. 



90. Eeasoning from a few facts, and from the ana- 

 logy of the higher orders in the animal kingdom, it 

 has been believed that all vegetable hybrids are 

 sterile ; and, when sterility is not the consequence 

 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 



