286 Dr Morton on Hybrid animals and Plants. 



and the cabbage ; the former bearing a short pod or silicula, 

 the latter a long pod or siliqua. 



Remarks. 



While we admit that hybrids, as a general law, are con- 

 trary to nature, we are also compelled to concede that this 

 law has very many exceptions. " It is manifest," says Dr 

 Prichard, " that there is some principle in nature which pre- 

 vents the intermixture of species, and maintains the order 

 and variety of the animal creation. If different species mixed 

 their breed, and hybrid races were often propagated, the ani- 

 mal world would present a scene of confusion. By what me- 

 thod is this confusion prevented ? The fact seems to be, that 

 the tribes of wild animals are preserved distinct, not only by 

 the sterility of mules, but that such animals are never, in the 

 state of nature, brought into existence. The separation of 

 distinct species is sufficiently provided for by the natural re- 

 jyugnance between individuals of different kinds. This is, in- 

 deed, overcome in the state of domestication^ in which the na- 

 tural propensities cease, in a great measure, to direct their 

 actions.* 



But we have seen that mules are not always steril, and 

 also that hybrids are really produced in a state of nature, 

 wholly independent of the influence of cultivation ; facts which, 

 indeed, are admitted and illustrated by Dr Prichard in his 

 later writings. That domestication evolves the faculty of 

 hybridity there can be no question ; and we would apply the 

 principle to various classes of animals. It will materially 

 assist in explaining so great a variety in some animals, by 

 pointing, as De Azara and Hamilton Smith have suggested, 

 to certain primitive species, which were endowed with the 

 capacity for reproducing among themselves, especially under 

 the influence of domestic culture. We have shewn that this 

 fact is unquestionable among some quadrupeds and some 

 birds, of which the hybrid varieties have been cultivated for 

 the uses of man. 



* Researches into the Physical History of Mankind, i., p. 97. Second Edition. 



