238 MR. E, B. POULTON ON THE PROTECTIVE [Mar. 1, 



forms also probably gain to some extent by the greater publicity 

 which follows from the resemblance. We therefore see that the 

 force which tends towards the acquisition of similar forms of colour 

 and marking in widely different organisms is itself the resultant of 

 other forces varying in relative amounts in the different species. 

 Of these primary forces we have been enabled to detect two in the 

 majority of cases, and three in the minority, i. e. (1) The feasibility 

 of certain colours and patterns depending upon their effect on the 

 vertebrate eye, and thus giving the enemies as easy an education as 

 possible ; (2) The advantage of facilitating the education of enemies 

 hj giving them a small number of patterns and colours to learn ; 

 and (3) The great additional advantage conferred by trading upon 

 the reputation of a well-known and much-feared or much-disliked 

 insect. 



These may probably be looked upon as the chief primary forces 

 which have determined the various forms of conspicuous appearance. 

 But such forces have had very different material to work upon in 

 the different species, and doubtless the resultant has been largely 

 influenced by the protective colours which existed before the "warning" 

 colours and markings arose, and which formed the material on 

 which the first steps (at any rate) were built. We can, in fact, 

 point to certain conditions in the "warning" appearance of some species 

 which are almost certainly remnants of a previous mode of defence 

 due to protective coloration. Thus Prof. Meldola has drawn my 

 attention to an opinion expressed by Mr. T. W. Wood (" Insects in 

 Disguise," Student, 1868), that the larvae of ^.yorco5<«« are protected 

 by their resemblance to the flowers of the ragwort. I believe that 

 in the orange ground-colour of this species we have such a remnant 

 of a former resemblance to the flowers of this plant and the groundsel, 

 on which the species also feeds. The acquisition of the black bands 

 and, above all, the gregarious habits are, then, later developments 

 which have followed the acquisition of an unpleasant taste. Here it 

 is seen that the material at the disposal of the primary forces 

 tending towards a " warning " appearance was such as to render 

 most probable the resultant which has actually obtained. 



Again, Mr. Thomas Eedle informed Prof. Meldola that he beheved 

 the larva of C. verbasci resembles the flowers of its food-plant, 

 mullein. Here, again, I entirely agree with this observation. There 

 is a great deal in the larva which harmonizes extremely well with 

 the yellow and dark sessile flowers, studded upon the surface of the 

 thick green spike, and surrounded by green unopened flowers. Tn 

 this case it is probable that the pattern may have been rendered a 

 little more distinct ; but the very conspicuous appearance practically 

 depends upon the gregarious habit, and upon the fact that the larvae 

 do not chiefly rest upon the spike, but are commonly seen upon the 

 uppersides of the large leaves, forming a background against which 

 the larval colours appear with startling distinctness. But, as Mr. 

 Eedle maintains, an isolated larva on the flowering-spike is evidently 

 well protected by colour-harmony with its surroundings. These are 

 but instances of the past history which must be deciphered before we 



