214 THE CROSSING, &C, OF PIGEONS AND FOWLS. 



Another close miss is made, below, at the true 

 law. 



"Facts teach us," says he (p. 282, Vol. ii, Animals 

 and Plants, &c), "a valuable lesson; namely, that we 

 ought to be extremely cautious in judging what char- 

 acters are of importance, in a state of nature, to animals 

 and plants." 



This question is solved, to a nicety, by the process 

 of close-interbreeding. If great evil flows from such a 

 process, there are many characters wanting, which are 

 of importance : If no evils flow from any interbreeding, 

 however close or however prolonged, all of the charac- 

 ters of importance are present in the individual : All 

 of the positive characters of the given species, are in'a 

 physiological view, of importance ; both, in a state of 

 nature, and in a state of domestication. 

 , It is manifest, that, if the theory of reversion, or pro- 

 portionate development be true, it must be impossible 

 for any of these divergent varieties to transmit its type 

 for any great length of time, in an unbroken line of de- 

 scent. Such is the fact. The long-continued inter- 

 breeding of animals, lacking so many of the characters 

 of their species, would necessarily occasion debilitated 

 constitutions incompatible with existence, and also 

 occasion complete sterility. The history of the differ- 

 ent breeds, respectively, of the Pigeon, of the Fowl, 

 and of the Pig, reveals that such has been the case; 

 that it is, and has ever been, necessary, frequently to 

 replenish the stock of such breeds, by means of cross- 

 ing, and by accessions, or the new selection of such 

 varieties, from the races under nature, or from the less 



