INTRODUCTION. 107 



This distribution is sufficiently correct, in a gene- 

 ral point of view, to merit consideration ; and the 

 modifications which can be pointed out in the habi- 

 tat may well be ascribed to the migrations of man, 

 the necessity of administering to his wants and his 

 pleasures, and therefore to his particular care ; 

 which, after all, never enabled him to carry out his 

 desires beyond the few degrees of cold and heat, 

 one way or the other. If, then, by their conforma- 

 tion, these animals were not invincibly debarred the 

 faculty of breeding together and producing prolific 

 lines of descent, we would find the great variety of 

 races of dogs now existing completely accounted 

 for by the demoralization they have sufi^ered from 

 slavery. For although the laws which bind organized 

 beings within the prescribed limits of given ana- 

 tomical and external consimilarities, still that power 

 whence these laws emanated, has also shown itself 

 in their exceptions. Exceptions that would in all 

 probability be much more numerous, if our know- 

 ledge was more extended and accurate. Some have 

 been already pointed out, others are known to exist 

 in other classes of animals, as in birds organized on 

 a difi'erent but not an inferior plan, such as the hy- 

 brid between difi'erent species of ducks, as well as 

 finches, whose ofi*spring are equally prolific and 

 continuous. 



To the objection that in this manner the difficulty 

 of the question is avoided but not overcome, we 

 answer, that the foregoing arguments tend at least 

 to support the general inference, and that we do not 



