INTRODUCTION. 2b 



are a mixture of the Malay with the Negro in New Guinea and 

 the neighboring islands; according to Lesson, most of them are a 

 frail and feeble race. We hence derive conclusive proof, unless 

 there be in the human races an exception to this admitted law of 

 nature, that all the tribes of men belong to one species and family. 



If we could compare our breeds of domestic animals with their 

 original wild stocks, we could easily ascertain the limits of variation 

 in these breeds ; but the wild originals cannot now 1m' recognized. 

 However, in the animals known to have been imported into America 

 from Europe since the fifteenth century, we have an abundance of 

 materials fur interesting observations; these animals have greatly 

 multiplied, and many, running wild in the forests, have lost all 

 appearances of domestication ; the wild tribes are physically differ- 

 ent from their tame originals, and there i* reason to believe that the 

 change is in the direction of the wild stocks from which the tame 

 animals originated. 



The hogs of the forest very nearly resemble the wild boar ; their 

 ears have become erect ; their color has changed to black ; instead 

 of hair and bristles, their skin is covered with thick, often crisp fur, 

 under which is sometimes a species of wool ; their heads become 

 larger; indeed, they are returning gradually to the appearance of 

 the wild boar of Europe. The difference between the skulls of the 

 domestic hog and the wild boar is as great as that between the Euro- 

 pean and the Negro skull. The horse, the ass, the cow, the sheep, 

 the goat, the dog, and gallinaceous fowls, show similar changes, and 

 a tendency to return to the primitive wild type. Even the func- 

 tions of animal life may be greatly changed in a few generations. 

 It is not natural for the cow, any more than for other female animals, 

 to yield milk when she has no young to nourish ; the permanent pro- 

 duction of milk is a modified animal function, produced by an artifi- 

 cial habit for several generations. In Colombia, the practice of 

 milking cows having been laid aside, the natural* state of the func- 

 tion has been restored ; the secretion of milk continues only during 

 the suckling of the calf, and is only an occasional phenomenon. 

 Says Roulin, " If the calf dies, the milk ceases to flow, and it is 

 only by keeping him with his dam by day that an opportunity of 

 obtaining milk from cows by night can be found." The horses 

 on the table land of the Cordilleras are taught very early a sort of 

 running amble, quite different from their natural gait ; these horses 

 become the sires of a race to which the ambling pace is natural, 

 and requires no teaching. The dogs employed in hunting the pec- 

 cary are taught the peculiar way necessary to take this animal ; 

 their offspring inherit as an instinct the lesson of their fathers, and 



