1877.] with some notes on Protective EesemUance. 29 



interesting that I must beg your attention to this branch of it at 

 some future time. 



The word ' mimicry ' as apphed to these now well-known facts 

 is open to objection, inasmuch as it seems to express an active 

 imitation, whereas the species accused of mimicry are of course 

 passive. On the other hand, the term is precise as expressing 

 a superficial as distinguished from a fundamental similitude. 

 " Protective resemblance " is a better term in some respects, but 

 this embraces a far wider group of facts. " Protective resem- 

 blance" might be applied, and is applied, to the resemblance of live 

 animals to stones, sticks, rotten wood, bark, lichens, dead or rolled 

 leaves, the dung of animals, &c., whereas " mimicry " can be only 

 applied to the assimilation of one living being to another. It 

 seems then desirable to retain the word " mimicry," since it can 

 hardly be said to mislead, in order to'define a branch of so wide a 

 subject. 



The phenomena of mimicry thus limited and characterized by 

 laws are thought to be at once a subtil and a definite proof of the 

 theory of the transmutation of species by natural selection. All, 

 however, that can be fairly said is, that these phenomena are 

 readily explained by that theory, and thus add to that vast cumu- 

 lative proof which is the only one of which the theory is capable. 

 Those who advocate the doctrine of fixity of species, and living in 

 a universe where forces infringing on matter operate in such com- 

 plicated combinations and antagonisms that the most stable and 

 inert substances are liable to change and are reconstructed, yet 

 believe that the most differentiated and complex organisms, com- 

 posed of the most - unstable and complex molecules, are the only 

 bodies characterized by immobility, (these) can with facility add to 

 the sum of their numerous unsupported hypotheses the conjecture 

 that both the imitator and the imitated were not only so con- 

 stituted from the beginning, but are held in their present relation- 

 ship as to the relative number of their individuals and also as to 

 their several enemies, by which alone the phenomena of mimicry 

 can be teleological or rational. 



All, however, that is required for the reception of any theory 

 is that it shall explain more phenomena than any other theory, 

 and be not absolutely inconsistent with any proven fact. These 

 facts of mimicry appear to contribute to the mass of facts which 

 this theory explains, but I cannot think that they afford definite 

 proof of the theory. 



Perhaps I may be allowed to refer to another connected resem- 

 blance. Long before these curious similitudes had received the 

 explanation which I believe Mr Bates first originated, a nearly 

 allied form of this dipterous insect resident in England received 

 the name Asilus crabroniformis, from its likeness to our hornet. 



