CONSCIOUS PROTECTIVE RESEMBLANCE. 545 



palaeontology for evidence as to these phenomena ; thus, if we are denied 

 the right of attempting to explain them by causes acting at the present 

 time, we shall have to abandon the whole question in despair. But, 

 what is more important, mimicry and resemblance are only particular 

 aspects of the principle of natural selection, and therefore if the factors 

 of mimicry do not exist to-day, then, a posteriori, neither do those of 

 natural selection. A single glance at nature is sufficient to justify the 

 rejection of such a conclusion, and we must, therefore, admit that the 

 factors of mimicry are in actual operation now ; were they not, we 

 should have no grounds for assuming that they had operated in past 

 geological epochs. If, therefore, we find that certain cases appear 

 difficult of exact explanation in the present state of our knowledge, we 

 are by no means justified in disposing of the difficulty by referring them 

 to causes operating only in the dim past, which we can neither prove 

 nor disprove. Rather must we continue the laborious search for further 

 evidence, not by a study of the anatomy of extinct animals, but by 

 seeking a deeper and more intimate knowledge of the real life -histories 

 of living organisms ; for we are still profoundly ignorant of the im- 

 mensely complex factors which go to make up the conditions of life of 

 the very commonest animal upon this earth. 



Nevertheless, it must be conceded as possible that there may be 

 certain cases of mimicry or resemblance which cannot be attributed to 

 exact causes acting at the present time ; but these would be only ex- 

 ceptional, and would probably be due to a recent chauge in the enemies 

 or the general environment of the species. I say " recent " advisedly, 

 for we have very good grounds for believing that complicated protective 

 characters would gradually disappear soon after the need for them 

 ceased, whether this disappearance be attributed to pammixis or to 

 disuse. 



Later on, in the papers under consideration, we find an excellent 

 suggestion that all examples of mimicry and resemblance should be 

 classified under various headings, such as — Demonstrated — Suggested 

 or Probable — Disputed or Mistaken — Purposeless — or Active. If such 

 an arrangement could be thoroughly and carefully carried out, it 

 would be of considerable value to students of these phenomena. Mr. 

 Distant could, of course, only give us a mere sketch of the subject ; 

 but it is remarkable that there is not even a reference to the lengthy 

 and important paper by Prof. Poulton, who has so thoroughly identi- 

 fied himself with this line of research, on " The Experimental Proof 

 of the Protective Value of Colour and Markings in Insects in reference 

 to their Vertebrate Enemies " (Proc. Zool. Soc. 1887, pp. 191-274), in 

 which all the reliable experiments on British insects, up to that date, 



Zool. 4th ser. vol. IV., December, lisOO. 2 p 



