402 MY LIFE 



nature of these phenomena will be useful to show the great 

 interest of the subject. 



In all parts of the world there are certain insects which, 

 from a disagreeable smell or taste, are rarely attacked or 

 devoured by enemies. Such groups are said to be " protected," 

 and they almost always have distinctive and conspicuous 

 colours. In the Malay Archipelago there are several groups 

 of butterflies which have this kind of protection ; and one 

 group is colored black, with rich blue glosses and ornamented 

 with white bands or spots. These are excessively abundant, 

 and, having few enemies, they fly slowly. Now there are 

 also several different kinds of papilios, which in colour are 

 so exactly like these, that when on the wing they cannot be 

 distinguished, although they frequent the same places and 

 are often found intermingled. Other protected butterflies are 

 of paler colours with dark stripes, and these are also closely 

 imitated by other papilios. Altogether there are about fifteen 

 species which thus closely resemble protected butterflies 

 externally, although in structure and transformations they 

 have no affinity with them. In some cases both sexes possess 

 this resemblance, or " mimicry," as it is termed, but most fre- 

 quently it is the female only that is thus modified, especially 

 when she lays her eggs on low growing plants; while the 

 male, whose flight is stronger and can take care of himself, 

 does not possess it, and is often so different from his mate as 

 to have been considered a distinct species. 



This leads us to the phenomenon of dimorphism and 

 polymorphism, in which the females of one species present 

 two or three different forms. Several such cases occur in the 

 Malay Archipelago, in which there are two distinct kinds of 

 females, sometimes even three, to a single male, which differs 

 from either of them. In one case four females are known to 

 one male, though only two of them appear to occur in one 

 locality. These have been almost always described as dis- 

 tinct species, but observation has now proved them to be 

 one, and it has further been noticed that each of the females, 

 which are very unlike the male, resembles more or less 

 closely some " protected " species. It has also been proved 



