Masterpieces of Science 



feed on the substance it resembles, and when it 

 does, no reasonable connection can be shown 

 to exist between the supposed cause and the 

 effect produced. It was reserved for the 

 theory of natural selection to solve all these 

 problems, and many others which were not 

 at first supposed to be directly connected with 

 them. To make these latter intelligible, it will 

 be necessary to give a sketch of the whole series of 

 phenomena which may be classed under the head 

 of useful or protective resemblances. 



Concealment, more or less complete, is useful 

 to many animals, and absolutely essential to 

 some. . Those which have numerous enemies 

 from which they cannot escape by rapidity of 

 motion, find safety in concealment. Those 

 which prey upon others must also be so con- 

 stituted as not to alarm them by their presence 

 or their approach, or they would soon die of 

 hunger. Now, it is remarkable in how many 

 cases nature gives this boon to the animal, by 

 colouring it with such tints as may best serve to 

 enable it to escape from its enemies or to entrap 

 its prey. Desert animals as a rule are desert- 

 coloured. The lion is a typical example of this, 

 and must be almost invisible when crouched upon 

 the sand or among desert rocks and stones. 

 Antelopes are all more or less sandy-coloured. 

 The camel is pre-eminently so. The Egyptian 

 cat and the Pampas cat are. sandy or earth- 

 coloured. The Australian kangaroos are of the 

 same tints, and the original colour of the wild 

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