Contents 



or among desert rocks and stones. Larks, quails 

 and many other birds are so tinted and mottled that 

 their detection is difficult. The polar bear, living amid 

 ice and snow, is white. Reptiles and fish are so coloured 

 as to be almost invisible in the grass or gravel where 

 they rest. Many beetles and other insects are so like 

 the leaves or bark on which they feed that when motion- 

 less they cannot be discerned. Some butterflies 

 resemble dead, dry or decaying leaves so closely as to 

 elude discovery. Every individual better protected 

 by colour than others, has a better chance for life, and 

 of transmitting his hues. Harmless beetles and flies 

 are so like wasps and bees as to be left alone. . . 



HUXLEY, THOMAS H. 

 Evolution of the Horse 



The hoof of the horse is simply a greatly enlarged and 

 thickened nail: four of his five toes are reduced to 

 mere vestiges. His teeth are built of substances of 

 varying hardness: they wear away at different rates 

 presenting uneven grinding surfaces. Probable de- 

 scent of the horse, link by link, especially as traced 

 in the fossils of North America. Evolution has taken 

 a long time: how long the physicist and the astronomer 

 must decide. x 



HOWARD, LELAND O. 



Fighting Pests with Insect Allies 



A scale insect threatened with ruin the orchards of 

 California. Professor C. V. Riley decided that the 

 pest was a native of Australia. Mr. A. Hoebele ob- 

 serves in Australia that the pest is kept down by lady- 

 birds. These are accordingly sent to California where 

 they destroy the scale insect and restore prosperity 

 among the fruit-growers. Another pest, of olive 

 trees, is devoured by an imported ladybird of another 

 xi 



