Chance Resemblances 



347 



found on pebbles and on various plants and animals where 

 it can not by any stretch of the imagination serve a useful 

 function. The same, however, may be said of any particular 



a 



a be 



Fig. 88. Mimicry of the African Swallow- 

 tail Butterfly (Papilio dardamis cenea) 



The male, i, is quite constant in appearance. The fe- 

 male, a, however, occurs in three distinct forms, and each 

 of these bears a closer resemblance to butterflies of other 

 genera than it does to its own male. Thus, the form cenea, 

 2a, resembles Amauris echeria, 2b, which in turn resembles 

 Pseudacraea tarquinia, 2c. The form lippocoon, }a, re- 

 sembles Amauris niavius, }b, which in turn resembles 

 Etiralia walbergi, ^c. The form trophonins, 4a, resembles Danais chrysippus, 4b, and this 

 in turn resembles Diadema misippiis, 4c. The argument that these resemblances are of 

 protective value seems plausible, but experimental studies point rather to the presence of 

 numerous hereditary factors that bring about different patterns in the females. From 

 Gruenberg, Elementary Biology, published by Ginn & Company. 



pattern that we find in the wing of a butterfly or moth; 

 and the same may be said if a similar pattern is found in 

 an insect of a different family. In other words, there is 

 no reason for assuming that every detail which we can ob- 

 serve is of necessary advantage, or has arisen because of 

 natural selection. 



