My life : a record of events and opinions - Wallace-online.org

"SCIENTIFIC AND LITERARY WORK 209These are excessively abundant, and having fewenemies they fly slowly. Now there are also severaldifferent kinds of papilios, which in colour are soexactly like these, that when on the wing they cannotbe distinguished, although they frequent the sameplaces and are often found intermingled. Otherprotected butterflies are of paler colours with darkstripes, and these are also closely imitated by otherpapilios. Altogether there are about fifteen specieswhich thus closely resemble protected butterfliesexternally, although in structure and transformationsthey have no affinity with them. In some cases bothsexes possess this resemblance, or " mimicry," as it istermed, but most frequently it is the female only thatis thus modified, especially when she lays her eggson low-growing plants ; while the male, whose flightis stronger and who can take care of himself, does notpossess it, and is often so different from his mate asto have been considered a distinct species.This leads us to the phenomenon of dimorphismand polymorphism, in which the females of one speciespresent two or three different forms. Several suchcases occur in the Malay Archipelago, in which thereare two distinct kinds of females, sometimes eventhree, to a single male, which differs from either ofthem. In one case four females are known to onemale, though only two of them appear to occur in onelocality. These have been almost always describedas distinct species, but observation has now provedthem to be one, and it has further been noticed thateach of the females, which are very unlike the male,resembles more or less closely some " protectedspecies. It has also been proved by experimentalbreeding that eggs laid by any one of these femalesare capable of producing butterflies of all the differentP