ApeilI, 1898.] 



SCIENCE. 



435 



It will be remembered that Bates, in his 

 memorable paper (L c. p. 507), also brought 

 to notice the very close resemblances, or 

 apparent mimicries, which unquestionably 

 exist between species belonging to different 

 groups or subfamilies of protected distaste- 

 ful butterflies themselves ; but neither he 

 nor Wallace felt able to give any explana- 

 tion of these instances, which obviously 

 differed very materially from the cases of 

 mimicry of an unpalatable protected species 

 by a palatable unprotected one. Not until 

 1879 was there any elucidation of this side 

 of the matter, but in May of that year ap- 

 peared in 'Kosmos,' Fritz Miiller's notable 

 paper on ' Ituna and Thyridia,' which was 

 translated by Professor Meldola, and printed 

 in our ' Proceedings ' for the same year 

 (p. XX.). In this memoir Miiller made the 

 valuable suggestion that, the advantage de- 

 rivable from these resemblances between 

 protected forms was the division between 

 two species of the percentage of victims to 

 the inexperience of young insectivorous 

 enemies which every separate species, how- 

 ever well protected by distastefulness, 

 must pay. 



Professor Meldola not only brought for- 

 ward and supported, with all his wonted 

 grasp and acumen, F. Miiller's daring inter- 

 pretation of this phenomenon, but in 1882,* 

 in a paper discussing the objections bi-ought 

 against Miiller's view, made a distinct ad- 

 vance by showing how that view could 

 justly be extended to explain the character- 

 istic and peculiar prevalence of one type of 

 coloring and marking throughout numbers 

 of species in protected groups — so especially 

 noticeable in the subfamilies Danainse, Heli- 

 coniinse and Acrseinse. 



In 1887 was published f Professor Poul- 

 ton's most interesting memoir entitled ' The 

 Experimental Proof of the Protective Value 

 of Colors and Markings in Insects in refer- 



*Ann. and Mag. Nat. Hist. (5), X., pp. 417-425. 

 fProc. Zool. Soc. Lond., 1887, pp. 191-274. 



ence to their Vertebrate Enemies,' which 

 dealt in great detail with the actual results 

 of numerous experiments conducted by 

 himself and other naturalists with the ob- 

 ject of ascertaining to what extent highly 

 conspicuous (almost always distasteful) 

 larvte and perfect insects are rejected or 

 eaten by birds, lizards and frogs. The 

 conclusions given at the close of this paper 

 ("pp. 266-267) cover a wide range in con- 

 nection with the subject of warning colora- 

 tion, and among them I would call special 

 attention to ISTo. 5, in which the author 

 points out that " In the various species in 

 which a conspicuous appearance is pro- 

 duced by color and marking, the same 

 colors and patterns appear again and again 

 repeated," and adds that " In this waj' the 

 vertebrate enemies are only compelled to 

 learn a few types of appearance, and the 

 types themselves are of a kind which such 

 enemies most easily learn." This general- 

 ization certainly had the merit of first de- 

 tecting a great additional advantage deriv- 

 able from the common aspect exhibited by 

 a number of protected forms in the extended 

 ' Miillerian ' associations indicated by Pro- 

 fessor Meldola; and it was applied by Wal- 

 lace to the case of the Heliconiidse in the 

 comprehensive survey of warning colora- 

 tion and mimicry generally given in ' Dar- 

 winism' (Ch. IX., pp. 232-267, 1889). We 

 are further indebted to Professor Poulton 

 for the discussion and summary of all ex- 

 tant data up to 1890 in his ' Colors of 

 Animals,' a work which abounds in preg- 

 nant suggestion and indicates with justice 

 and clearness how far the evidence foi'th- 

 coming was valid and in what directions 

 evidence still lacking should be sought. 



Wallace well observed (' Darwinism,' p. 

 264) that " to set forth adequately the 

 varied and surprising facts of mimicry 

 would need a large and copiously illustrated 

 volume ; and no more interesting subject 

 could be taken up by a naturalist who has 



