242 MAMMALS IN THE WATER 



dormouse is as cold as death ; a tame rat, tested by a 

 clinical thermometer, showed a temperature of one 

 hundred degrees, and a live otter can scarcely be of 

 lower temperature than a live cat or a Cape ratel. The 

 Zoo caution, ' These animals bite/ precludes any effort 

 at taking their normal heat ; but that of a rat, which 

 takes to the water freely when the March winds are 

 blowing, is normal, and there is no reason to suppose 

 that that of the otter is different. 



As chill to the surface tissues is always dangerous to 

 warm-blooded creatures, in the absence of an inner 

 layer of fat which the whale, and, in some degree, the 

 polar bear, possesses, the fur must be the non-conductor 

 which protects them. Water, unless in movement, is 

 not a quick conductor of heat. The fur, aided by the 

 outer and longer hairs which keep it in place, holds the 

 water-jacket motionless, even if it reaches to the skin, 

 and this ' water compress ' saves the animal from a chill. 

 If the cold winds extract the warmth from it when 

 standing wet through on land, it takes to the water as 

 the relatively warmer element. 



