162 PROTECTIVE COLORING 



that they give the insect no exemption whatever 

 from the attack of ichneumons, — a fact which is 

 perfectly in accord with our knowledge of the physi- 

 ology of insect-vision. But as regards their more 

 highly organized enemies, it may indeed be doubted 

 whether there is a single one of our buttel-fly cater- 

 pillars which is not protected by means of its color, 

 either to prevent its being seen or to render it 

 conspicuous. Indeed, we are inclined to say with 

 Drummond that '' mimicry is not an occasional or 

 exceptional phenomenon, but an integral part of 

 the economy of nature. It is not a chance relation 

 between a few objects, but a system so widely 

 authorized that probably the whole animal king, 

 dom is more or less involved in it." 



