S4 NATURAL HISTORY OF THE DOG. 



shades ranging between, mark the degrees of heat and cold. 

 Most of the animals of high northern latitudes become of a lighter 

 hue as winter approaches, from a similar principle of adaptation 

 with that which also increases the quantity of their clothing ; the 

 light colour preventing the natural heat of the body escaping by 

 the active radiation which occurs from bodies more darkly clad. 

 The alteration in the general texture of these coverings, by the 

 effect of climate, is no less remarkable than that produced on their 

 colours. In the sterile and inhospitable regions, where ice and 

 snow hold a stern dominion, the quadrupeds are furnished with 

 a short fleecy tegument, which is rendered still warmer by 

 either a long and shaggy, or a short and crisp surtout of strong 

 hair. The feathers of alpine water-fowl conceal an immense mass 

 of the warmest down underneath, while the land birds of these 

 regions are feathered down to the very claws. To further exem- 

 plify the effects of climate, observe how different are the clothings 

 of the thick-fleeced dog of Baffin's Bay and the naked dog of Bar- 

 bary ; the dense woolly covering of the European sheep, and the 

 thin hair of those inhabiting hot countries. Contrast the glossy 

 tunic of the Arabian stallion with the shaggy coat of the Shetland 

 pony ; and further, it may be observed, that where, for the pur- 

 poses of beauty, nature has bestowed on the beasts of arid climes 

 a long coat or covering, it is commonly observed to be one whose 

 thin and silky texture can neither absorb the solar rays nor con- 

 fine the animal heat : this may be seen in the lengthened fine hair 

 of the goats, cats, and rabbits of Angora, and other eastern 

 countries. Our domesticated animals are even under the in- 

 fluence of climate, and, as winter advances, they are seen to 

 change their thin fine hair for one of longer and thicker texture. 

 Our horses in autumn prepare for the coming season, and change 

 their fine summer coat for one thicker and longer ; but, under an 

 artificial climate produced by hot stables and extra clothing, by 

 losing the stimulus of necessity, they retain the same appearance 

 throughout the year. Neither are the coverings of the body the 

 only parts that are subject to the effect of climate ; the form and 



