338 



Biology in America 



mid-rib and veins, as to deceive, at a little distance, the 

 closest observer. When in flight the butterfly is a striking 

 object, but let it alight, and lo, it vanishes from sight as 

 suddenly and completely as though the earth had swallowed 

 it up. 



But some animals, who have no enemies, unless it be man, 

 who has appeared on the scene of action only recently, in 

 terms of biological time, closely resemble their surroundings. 

 Perhaps the most notable example of this is the polar bear, 

 who lives among the snows and ice fields of the Arctic. His 

 color is readily explained, according to the Darwinians, on 

 the assumption of an aggressive resemblance. If the seal, 

 upon which the bear preys, cannot see the latter as he ap- 





IMITATION OP AN ORCHID (LEFT) BY A MANTIS (RIGHT) 

 Courtesy of Thomas Y. Crowell Publishing Company. 



preaches he will be more readily caught, so that in this way 

 a resemblance to his surroundings is of advantage to the 

 bear. 



Closely allied to this theory is that of alluring resem- 

 blance, according to which certain animals play the part of 

 a "wolf in sheep's clothing." One of the worst of these 

 hypocrites is the Indian mantis, which so closely resembles 

 an orchid blossom as (supposedly) to attract unwary insects, 

 who, alighting on it in search of honey, thereby come to an 

 untimely end. 



But by no means all animals are thus protectively colored. 

 Some on the contrary are so conspicuous that it seems as 

 if Nature had intentionally singled them out for objects of 

 remark. The monarch butterfly in his brilliant livery of 

 black and orange, the skunk in striking garb of black and 



