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spicuous features, such as venation; nor do they respect more than the nature 

 of things obliges them to do, the ties of blood-relationship. Then, again, it is 

 obvious why they occur in the same and not widely different localities ; in some 

 instances, as we have seen, their bearers actually flying in company and fre- 

 quenting the same flowers ; for the common aspect, supposing it to be in any 

 sense protective, wxjuld only take effect when the sharers in it were exposed to 

 the attacks of the same body of enemies ; that is to say, when they inhabited the 

 same locality. And this would be equally true, whether the warning colours 

 are shared between distasteful forms, or whether they are deceptively adopted 

 by forms rmprotected by inedibility ; — whether, in Professor Poulton's terms, 

 they are synaposematic or pseudaposematic. I do not enlarge upon this part of 

 the question, or upon the theories which arii know^l under the names of Bates 

 and Miiller respectively, because these theories have been fully dealt with else- 

 where, and I think I may assume that they are familiar to the greater part of 

 my he-arers. But that mistaken ideas as to what is really meant by protection 

 and mimicry still prevail in some quarters is evident from certain remarks of 

 Fruhstorfer in dealing with the genus Prioneris which we have just been dis- 

 cussing. 'Wallace,' he says, 'regards the "rarer" Prioneris as a mimetic 

 form of the " commoner " Delias. But I cannot accept his view, since mimicry 

 among the in all respects harmless Pierids appears no sort of protection, and 

 properly speaking the smooth-margined Delias should rather copy the armed 

 Prioneris if there is assumed to be mimici-y at a,ll.' If anyone has no better 

 knowledge than this of what is meant by the theory of mimicry, it is not won- 

 derful that he should consider the subject unworthy of serious attention. 



The warning-colour theory, then, gives a rational explanation both of the 

 superficial character of the resemblances and of the geographical factor in their 

 occurrence. But it obviously involves the reality of natural selection; and it 

 is here that some are disposed to part company with the upholders of the 

 theory. I have already referred to the fact that much positive evidence now 

 exists both that butterflies are eaten and that preferences on the part of their 

 enemies exist between one kind and another. I -will only remark in passing 

 that the objector on this score sometimes adopts an attitude which is scarcely 

 reasonable, arid which perhaps on that very account is somewhat hard to 

 combat. The kind of objector that I mean begins by saying that the destruction 

 of butterflies by hirds and other enemies is not sufficient to give play for the 

 operation of selection. You beg his pardon, and produce evidence of consider- 

 able butterfly destruction. To which he replies, '0, they are eaten, are they? 

 I thought you said they were protected.' This is a good dilemma, but the 

 dilemma is notoriousiy an unconvincing form of argument. If a reply be called 

 for it may he given like this : ' Butterflies are either preyed upon or they are 

 not. If they are, an opening is given for selection ; if they are not, it shows 

 the existence of some form of protection.' The essence of the matter is that 

 both the likes and dislikes of insectivorous animals, and the means of protection 

 enjoyed by their prey, are not absolute hut relative. A bird that will reject 

 an insect under some circumstances will capture it under some others ; it will, 

 for instance, avoid insect 'A' if it can get insect ' B,' but will feed on 'A' 

 if nothing else is to be had ; and it is probable that hardly any insect is entirely 

 proof against the attack of every kind of enemy. The relative nature of pro- 

 tection is readily admitted when the question is not one of mimicry or of warning 

 colours, but of protective resemblance to inanimate objects. All degrees of 

 disguise, from the rudimentary to the almost perfect, are employed ; the lower 

 degrees are allowed to be of some service, and on the other hand a disguise that 

 is almost completely deceptive may at times be penetrated. This consideration 

 applies also to the objection that the first beginnings of mimetic assimilation 

 can have no selective value. If the rough resemblance to an inanimate object 

 affords some amount of protection, though that amount may be relatively 

 small, why should not the same apply to the first suggestion on the part of a 

 mimic of an approach to the aposeme or warning colour of its model ? The 

 position that neither kind of assimilation is of service is intelligible, though not 

 common ; but there is no reason why benefit should be aflfirmed in the one case 

 and denied in the other. There are further considerations which tend to deprive 

 this latter criticism of force ; the fact, for instance, that a resemblance to one 



