218 HUXLEY AND NATURAL SELECTION 



that a modification in the pattern of any other conspicuous 

 butterfly which suggests the same experience and leads 

 to a cautious attack, or perhaps averts attack altogether, 

 will be advantageous. Both the genera to which the 

 mimics belong are certainly conspicuous, and it is probable 

 that they, too, are distasteful. It is, of course, necessary 

 that the same enemy should see both model and mimic ; 

 but, if this be achieved, it matters not how many hundreds 

 of miles may intervene between the two. The northern 

 mimics belong to genera of black, white-marked butter- 

 flies which have much in common with the black, white- 

 marked male of H. misippus ; so that it is not difficult to 

 understand why the latter species, rather than any other 

 distasteful resident of the tropical areas to the south, 

 has been imitated. There was, in fact, from the very 

 first, sufficient likeness for Natural Selection to work upon. 1 



The hypothesis here suggested demands inquiry into 

 the habits of the migratory birds of Western China, the 

 routes followed, and dates of arrival and departure. 



The consideration of Hypolimnas misippus as an 

 example of mimicry, and especially the striking fact that 

 its male is a model, while its female is a mimic, serves as 

 an illustration of the changes in interpretation wrought 

 by the accumulation of new observations. But the out- 

 come of such modifications — and they are taking place 

 everywhere in the field of natural history — is that Natural 

 Selection rests on an ever-broadening foundation. If it 

 were an erroneous or a merely inadequate theory of 

 evolution, would not the astonishing increase of know- 

 ledge again and again bring to light facts which are 

 absolutely irreconcilable with it ? 



The examples brought forward on the present occasion 

 are but a selection from a vast body of observations which 

 receive an intelligible interpretation under this theory, 

 but not under any other. 2 When accumulated facts, not 



1 See Report of the Delegates of the Oxford University Museum for 

 1904 in the Oxford University Gazette, 1905. 



2 For a detailed statement of the facts of mimicry in relation to 

 Natural Selection see Linn. Soc. Journ. Zool., vol. xxvi, pp. 558-612, 

 reprinted as Essay viii, p. 220. 



