CLIMATE AND COLOUR 13 



been exhausted. Yet even despite its colour- 

 ing, the tissue of the flesh is partly trans- 

 parent, so that actinic rays may kill bacilli, 

 and sunshine is used as a medicine for the sick. 

 But the rays which begin by killing germs may 

 be strong enough in time to burn the living 

 tissues. For that reason man and the greater 

 animals are armoured by red and yellow liquid 

 paints in the layers of skin, which vary in 

 strength and volume with the degree of sun- 

 light in each cUmate, from pale hues in cloudy 

 districts of low sun to an intense black in the 

 tropics. 



Stocks native to forest shelter such as men, 

 elephants and pigs are guarded only with skin 

 body colour. Those exposed to direct light — 

 horses, cattle and sheep, have also a coat of 

 hair as a second armour against the actinic 

 rays, and this also varies in colour with the 

 strength of sunshine, from white in the regions 

 of snow to the golden dun of lions and tigers, 

 the dun and bay of horses and the black of 

 many species in regions of strong light. 



In men and other animals there is Httle red 

 flesh covering for the brain, the spine and the 

 great gangUa of the nerve machinery. So 

 many animals like the lion and bison have 

 manes as an extra shield for the nerve centres. 



