314 Papers from the Marine Biological Laboratory at Tortugas. 



coloration that they are often impHed rather than expHcitly stated by 

 writers on the subject. I therefore quote the following detailed statement 

 by Wallace (1891, pp. 242-243) (the italicizing is mine) : 



But when they (the Heliconidae) first arose from some ancestral species or group 

 which, owing to the food of the larva or some other cause, possessed disagreeable 

 juices that caused them to be dishked by the usual enemies of their kind, they were 

 in all probability not very different either in form or coloration from many other 

 butterflies. They would at that time be subject to repeated attacks by insect eaters, 

 and, even if finally rejected, would often receive a fatal injury. Hence arose the 

 necessity of some distinguishing mark, by which the devourers of butterflies in general 

 might learn that these particular butterflies were uneatable ; and every variation lead- 

 ing to such distinction, whether by form, color, or mode of flight, was preserved and 

 accumulated by natural selection, till the ancestral Heliconidas became well distin- 

 guished from eatable butterflies, and thenceforth comparatively free from persecution. 



CRITICISM OF THE THEORY OF WARNING COLORATION. 



(a) With reference to tenet II (a) above. Since palatable forms can 

 not be conspicuous and at the same time accessible to their vertebrate foes, 

 it follows that unpalatability must (assuming it to have appeared after in- 

 sectivorous vertebrates) have arisen among inconspicuous insects and these 

 inconspicuous forms must subsequently have become conspicuous. This 

 accords with the statement of Poulton (1890, p. 176") : "it must be remem- 

 bered that an unpleasant attribute must always appear in advance of the 

 warning color " and also with the existence at the present time of un- 

 palatable insects that are protectively colored (Mana typica, Beddard, 1892; 

 Mancstra persicariae, Beddard, 1892, and many others). That there is 

 no necessary physiological relation between the unpleasant properties of 

 the body juices and conspicuous coloration is shown by the existence of 

 these alleged unpleasant juices in protectively-colored forms, and their ab- 

 sence in certain conspicuous forms. Thus Wallace (1891, p. 254) says: 

 " The eatable butterflies comprise not only brown or white species, but hun- 

 dreds of Nymphalids, Papilionidae, Lycaenidse, etc., which are gaily colored 

 and of an immense variety of patterns." (See also the table of Beddard, 

 1892, pp. 164-165.) It is further shown by the coexistence of conspicuous 

 coloration with disagreeable attributes other than unpleasant juices (stings, 

 pricking hairs, Poulton, 1891). The manner in which warning colors are 

 held to have been developed in unpalatable insects is indicated by the above 

 quotation from Wallace. 



This mode of origin implies the possession by insectivorous vertebrates 

 of a considerable nicety of discrimination, concerning the existence of which 

 we do not appear to have experimental evidence. But the facts of mimicrv 

 seem to afford indirect evidence of well-developed powers of discrimination 

 in insectivorous vertebrates. We have no other explanation of mimicry 

 among Lepidoptera than that aiTorded by the theory of natural selection, 

 and a careful examination of the evidence on which the theory of mimicry 



