

Chap. XXVIII. CONCLUDING REMARKS. 407 



rear, for instance, curious breeds of the fowl, pigeon, or canary- 

 bird. 



From several causes it is difficult to judge of the amount 

 of modification which our domestic productions have under- 

 gone. In some cases the primitive parent-stock has become 

 extinct, or cannot be recognised with certainty owing to. its 

 supposed descendants having been so much modified. In 

 other cases two or more closely allied forms, after being do- 

 mesticated, have crossed; and then it is difficult to estimate 

 how much of the change ought to be attributed to variation. 

 But the degree to which our domestic breeds have been modified 

 by the crossing of distinct natural forms has probably been 

 exaggerated by some authors. A few individuals of one form 

 would seldom permanently affect another form existing in much 

 greater numbers ; for, without careful selection, the stain of the 

 foreign blood would soon be obliterated, and during early and 

 barbarous times, when our animals were first domesticated, 

 such care would seldom have been taken. 



There is good reason to believe that several of the breeds of 

 the dog, ox, pig, and of some other animals, are respectively 

 descended from distinct wild prototypes ; nevertheless the belief 

 in the multiple origin of our domesticated animals has been 

 extended by some few naturalists and by many breeders to an 

 unauthorised extent. Breeders refuse to look at the whole 

 subject under a single point of view ; I have heard one, who 

 maintained that our fowls were the descendants of at least 

 half-a-dozen aboriginal species, protest that he was in no way 

 concerned with the origin of pigeons, ducks, rabbits, horses, or 

 any other animal. They overlook the improbability of many 

 species having been domesticated at an early and barbarous 

 period. They do not consider the improbability of species 

 having existed in a state of nature which, if like our present 

 domestic breeds, would have been highly abnormal in comparison 

 with all their congeners. They maintain that certain species, 

 which formerly existed, have become extinct or unknown, 

 although the world is now so much better known. The assump- 

 tion of so much recent extinction is no difficulty in their eyes ; 

 for they do not judge of its probability by the facility or difficulty 

 of the extinction of other closely allied wild forms. Lastly, 



