168 ANIMAL LIFE IN DESERTS 



evaporate more water than a similar buff creature, 

 if it is to keep its body temperature below a certain 

 figure on a particular day. This, one would sup- 

 pose, would severely handicap the black creatures 

 under circumstances in which water is extremely 

 scarce. 



And then, again, why in particular do Eugaster 

 and CalUptamus coelesyriensis and the Wheatears 

 become black, for it is against their family tradi- 

 tions ? The Raven and Tenebrionids and the 

 Scarab, we may suppose, are black because the 

 colour is ancestral and they found no reason to 

 alter it ; but the Eugaster and CalUptamus and 

 Wheatears have broken with aU tradition, and at 

 present we cannot explain their blackness. 



I maintain, then, that protective coloration cannot 

 be accepted as a theory to explain the very remark- 

 able coloration of desert animals. It is not easy 

 to apply it to animals which hunt or are hunted 

 at night ; or to animals which appear to be without 

 any large enemies more powerful than themselves, or 

 to animals whose paUid colour extends to their beUies 

 and the soles of their feet. It cannot be appHed at aU 

 to subterranean animals, nor to black animals, nor to 

 those whose colour would protect them if their 

 habits were radically altered. I do not deny that 

 protection is afforded by colour, under certain cir- 

 cumstances, to certain animals : on the contrary I 

 readily admit that many desert animals are rendered 

 invisible by their colour, which harmonizes per- 

 fectly with their particular environment : most of 

 these animals are invertebrates and not rapid in 



