290 Colour and the Struggle for Life 



is well known that when the sexes differ the females are almost 

 invariably more perfectly mimetic than the males and in a high 

 proportion of cases are mimetic while the males are non-mimetic. 



The difficulty was met several years later by Fritz Muller's well- 

 known theory, published in 1879\ and immediately translated by 

 Meldola and brought before the Entomological Society 2 . Darwin's 

 letter to Meldola dated June 6, 1879, shows "that the first intro- 

 duction of this new and most suggestive hypothesis into this country 

 was due to the direct influence of Darwin himself, who brought it 

 before the notice of the one man who was likely to appreciate it 

 at its true value and to find the means for its presentation to English 

 naturalists 3 ." Of the hypothesis itself Darwin wrote "F. Muller's 

 view of the mutual protection was quite new to me 4 ." The hypo- 

 thesis of Miillerian mimicry was at first strongly opposed. Bates 

 himself could never make up his mind to accept it. As the Fellows 

 were walking out of the meeting at which Professor Meldola explained 

 the hypothesis, an eminent entomologist, now deceased, was heard to 

 say to Bates: "It's a case of save me from my friends!" The new 

 ideas encountered and still encounter to a great extent the difficulty 

 that the theory of Bates had so completely penetrated the literature 

 of natural history. The present writer has observed that naturalists 

 who have not thoroughly absorbed the older hypothesis are usually 

 far more impressed by the newer one than are those whose allegiance 

 has already been rendered. The acceptance of Natural Selection itself 

 was at first hindered by similar causes, as Darwin clearly recognised : 

 "If you argue about the non-acceptance of Natural Selection, it seems 

 to me a very striking fact that the Newtonian theory of gravitation, 

 which seems to every one now so certain and plain, was rejected by a 

 man so extraordinarily able as Leibnitz. The truth will not penetrate 

 a preoccupied mind 5 ." 



There are many naturalists, especially students of insects, who 

 appear to entertain an inveterate hostility to any theory of mimicry. 

 Some of them are eager investigators in the fascinating field of 

 geographical distribution, so essential for the study of Mimicry itself. 

 The changes of pattern undergone by a species of Erebia as we follow 

 it over different parts of the mountain ranges of Europe is indeed 

 a most interesting inquiry, but not more so than the differences 

 between e.g. the Acraea johnstmii of S.E. Rhodesia and of Kiliman- 

 jaro. A naturalist who is interested by the Erebia should be equally 

 interested by the Acraea ; and so he would be if the student of 



1 Kosmos, May 1879, p. 100. 2 Proc. Ent. Soc. Lond. 1879, p. xx. 



3 Charles Darwin and the Theory of Natural Selection, p. 214. 4 Ibid. p. 213. 



s To Sir J. Hooker, July 28, 1868, More Letters, i. p. 305. See also the letter to 

 A. R. Wallace, April 30, 1868, in More Letters, n. p. 77, lines 6—8 from top. 





