270 COVERING OF ANIMALS. 



changes in external circumstances, nor have they the sagacity 

 to avail themselves'of other means for protecting themselves 

 from the influence of cold and heat. Each species of animals 

 is generally confined to some particular portion of the earth, 

 and it is with difficulty that many of them are made to sur- 

 vive, for a long time, any great change of climate. To a 

 certain extent, however, nature has provided means for ob- 

 viating the bad effects which would be produced upon them 

 by the different temperatures of the seasons and of different 

 climates. These means are, a change in the quantity and 

 color of the hair, fur, or feathers, with which they are cov- 

 ered ; migration during the winter to warmer climates ; or 

 passing it in a state of torpidity. 



' In the colder regions of the earth, animals are covered 

 with thick and warm fur. In the warm, they are only cloth- 

 ed with hairs thinly scattered, or have a skin entirely naked. 

 The contrast is more striking where the same kind of animals, 

 or kinds closely resembling each other, inhabit different cli- 

 mates. In the dogs of Guinea and in the African and Indian 

 sheep, the fur is so thin that they may be almost denominated 

 naked. In the Siberian dog and Iceland sheep, on the other 

 hand, the body is protected by a thicker and longer covering. 

 In the swine of warm countries, we find a covering of bristles, 

 thinly scattered, and of a uniform size and texture ; but in 

 colder countries, there is, beside this covering, another of 

 fine, frizzled wool next to the skin, through which the bristles 

 project. The elephant of the warm regions has scarcely any 

 hair upon his body, whilst that species which is supposed to 

 be now extinct, but to have formerly inhabited the northern 

 parts of both continents, was clothed with a thick and warm 

 fur ; as is proved from the discovery of a carcass which had 

 been preserved in a frozen state, probably for some thousand 

 years, in the ice of Siberia. 



'In the same climate, the quantity of covering is accommo- 

 dated to the alternations of the seasons. At the approach of 

 winter, the hair is increased in quantity and in length, as may 

 be observed in any of our domestic animals; and this increase 

 is proportioned to the rigor and severity of the season. On 

 the contrary, at the return of the warm season, the fur be- 

 comes thin. Hence, .those animals which are sought for the 

 sake of their fur, must be hunted in the winter ; and it has 

 been observed that, where the beginning of the season is 

 mild, and the cold weather late in setting in, the hair is also 

 backward, and that a few days of cold will produce a percep. 



