ADAPTATION OF ORGANISMS 323 



contrast with the animal's usual background. Sometimes, 

 however, the contrast which is so striking with the bird in 

 the hand, proves to be 'obliterative' with the bird in the 

 bush a conspicuous color pattern, expressing gradations 

 of light and shadow, and counter shading, fuses with a 

 background of light and shadow afforded by foliage. 



But examples of color patterns which by the most liberal 

 stretch of the imagination cannot be interpreted as harmoni- 



FIG. 174. 'Protective Mimicry.' A, drone Honey Bee; B, a Bee-fly, 

 Eristalis tenax. (From Folsom.) 



ous with the animal's usual surroundings are not far to 

 seek. Brilliant yellows and reds render, for instance, many 

 Wasps, Bees, Butterflies, and various species of Snakes actu- 

 ally conspicuous. And it is suggestive that very many of 

 these forms are provided with special means of defense, such 

 as poison glands and formidable jaws, or special secretions 

 which render them unpalatable. Moreover, what is still 

 more interesting, many animals possessing this 'protective 

 conspicuousness' which renders them easily identified and 

 advertises that they are to be avoided by their foes, are 

 frequently 'mimicked' in color pattern and form by defenseless 

 creatures. Thus commonly associating with the various 

 species of Bees hovering about flowers are defenceless Flies 

 which are so bee-like in appearance that they are usually mis- 



