CONSCIOUS PROTECTIVE RESEMBLANCE. 345 
paleontology 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 change 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 Hnemies” (Proc. Zool. Soc. 1887, pp. 191-274), in 
which all the reliable experiments on British insects, up to that date, 
