TRUE MIMICRY 



95 



locally separate, so that each is exclusively restricted to a particular 

 region, for their areas of distribution often overlap, and, at the Cape 

 for instance, one male form and three different forms of female have 

 been reared from one set of eggs. In addition, we have the fact that 

 between the two local forms of Danais echeria transition forms occur, 

 and that the mimetic females of Papilio merope show the same transition 

 forms locally, and we must admit that all these facts harmonize most 

 beautifully with the selection interpretation, but defy any other. And 

 that the last doubt may be dispelled, nature has preserved the primi- 

 tive female form on the continent of Africa— namely, in Abyssinia, 

 where, along with the mimetic females, there are others which are 

 tailed like the males (PL I, Fig. i), and are like them in form and 

 colour, a few minor differences excepted. 



Thus we have in Papilio merope a species which, in the course 

 of its distribution through Africa, has scarcely varied at all in the 

 male sex, but in the female has almost everywhere lost the outward 

 appearance of a Papilio, and has assumed that of a Danaid, which is 

 protected by being unpalatable, and not even everywhere the 

 appearance of the same species, but in each place that of the 

 prevailing one, and sometimes of several in one region. These 

 females thus show at the present day a polymorphism which consists 

 of four chief mimetic forms, to which has to be added the primitive 

 form — that resembling the male. This has survived in Abyssinia 

 alone, and even there it is not the only one, but occurs along with 

 some of the mimetic forms. 



To the question why only the females are mimetic in this and 

 other cases, Darwin and Wallace have answered that the females are 

 more in need of protection. In the first place, the males among 

 butterflies are considerably in the majority, and, secondly, the females 

 must live longer in order to be able to lay their eggs. Moreover, the 

 females, which are loaded with numerous eggs, are heavier in flight, 

 and during the whole period of egg-laying — that is, for a considerable 

 time — they are exposed to the attacks of numerous enemies. Whether 

 one of the abundant males is devoured sooner or later is immaterial to 

 the persistence of the species, since one male is sufficient to fertilize 

 several females. The death of a single female, on the other hand, 

 implies a loss of several hundred descendants to the species. It 

 is, therefore, intelligible that, in species already somewhat rare, the 

 female must first of all be protected ; that is to say, that all variations 

 tending in the direction of her protection would give rise to a 

 process of selection resulting in an augmentation of the protective 

 characters. 



