23 



laws, and the living organisms are merely the counters in 

 Nature's great game. We find it difficult, however, to avoid 

 using terms which seem to imply intention and design both on the 

 side of the moulding forces and the creatures subjected thereto. 



In order to understand protective mimicry aright, you must 

 first pay attention to what naturalists speak of as warning 

 colouration. A long time ago it excited surprise among students 

 of nature that some of the very feeblest of living beings, instead 

 of hiding away from their enemies, in accordance with the general 

 rule, flaunt their conspicuous colours abroad in the moat bare- 

 faced and reckless manner. When Darwin was studying the 

 colours of animals, he at one time was in danger of being led 

 away by enthusiasm for one of his pet theories. This was the 

 theory of sexual selection. He found that many birds put on 

 gay plumage in the spring, and that male and female butterflies 

 seemed to seek one another because of their brilliant colours. 

 But at the time when he was inclined to attribute most bright 

 colours found among animals to the needs of courtship, he was 

 somewhat taken aback on finding that certain caterpillars, who 

 resemble angels in one particular, in that they do not marry or 

 are given in marriage, were in the habit of wearing very marked 

 and conspicuous attire. He wrote to his great coadjutor, Alfred 

 Kussell Wallace, about the subject, and got the reply that in all 

 probability it would be found that birds refuse to eat conspicuous 

 larvEe because they have some nauseous taste or smell, or some 

 other property which renders them unfit for food. I must quote 

 you a few words of Darwin's reply to Wallace's communicatiou. 

 He wrote : — " You are the man to refer to in a difficulty. I 

 never heard anything more ingenious than your sus^gestiou, and 

 I hope you may be able to prove it true. That is a splendid fact 

 about the white moths, and it warms one's very blood to see h 

 theory thus almost proved to be true " Now Wallace, in 

 conjunction with his other preat colleague, Henry Walter Bates, 

 did prove this theory to be true ; and it is a striking illustration 

 of how one discovery in science often at once leads to other 

 discoveries even more brilliant, that from these observations 

 sprang our knowledge of the marvellous facts of protective 

 mimicry. We now know, without need of experiment, that a 

 weak and conspicuous animal which makes no attempt to hide 

 itself, is almost cer'ainly inedible to the birds, lizards, etc., 

 which are in the habit of preying upon insects. There are certain 

 striking exceptions to this rule, and as these exceptions form the 

 very subject of this paper, we must by no means ignore them. 



These exceptions are the creatures which have so mimicked 



