CAUSE OP EVOLUTION 391 



hive when the pollen is scarce, of which these consume an 

 enormous quantity. In a state of nature in the heart of 

 their native forests in Asiatic valleys, where they existed 

 probably long before the tertiary epoch, the bees can 

 evidently never have met with a substance of this kind. 

 And yet, if care be taken to 'bait' some of them with it 

 by placing- them on the floor, they will touch it and test 

 it; they will perceive that its properties more or less re- 

 semble those possessed by the dust of the anthers ; they 

 will spread the news among their sisters and we shall 

 soon find every forager hastening to this unexpected, 

 incomprehensible food, which in their hereditary mem- 

 ory must be inseparable from the calyx of flowers where 

 their flight for so many centuries past has been sumptu- 

 ously and voluptuously welcomed." 



The brain of the bee, which directs all its actions, con- 

 tains but few cells. The power that nearly all cater- 

 pillars or young butterflies have of changing their color to 

 harmonize with the place in which they are living is cer- 

 tainly wonderful, and its value has not been understood 

 by man until lately. During this last European war, the 

 following article appeared in my paper on the subject: 

 "A striking instance of the application of scientific 

 knowledge to the purpose of war is the color of the Ger- 

 man service uniform, a kind of invisible grey-yellow- 

 green, which blends with the prevailing hue of a land- 

 scape, so that bodies of troops become as it were con- 

 cealed in a chromatic haze. 



"Naturalists have long been familiar with 'protective 

 coloration', which is found among many species of insect 

 and other animals, and it is rather surprising that this 

 principle, which science declares to be a result of evolu- 

 tionary adaptation, has not sooner been employed in the 

 apparelling of armies. Khaki uniforms, whichuhave been 



