• LIFE IN LONDON 407 



whole question when writing my " Island Life," twelve years 

 later. 



As soon as the proofs of the " Malay Archipelago " were 

 out of my hands, I began the preparation of a small volume 

 of my scattered articles dealing with various aspects of the 

 theory of Natural Selection. Many of these had appeared 

 in little known periodicals, and were now carefully revised, 

 or partially rewritten, while two new ones were added. The 

 longest article, occupying nearly a quarter of the volume, 

 was one which I had written in 1865-6, but which was not 

 published (in the Westminster Review) till July, 1867, and 

 was entitled " Mimicry, and other Protective Resemblances 

 among Animals." In this article I endeavoured to give a 

 general account of the whole subject of protective resemblance, 

 of which theory, what was termed by Bates " mimicry," is a 

 very curious special case. I called attention to the wide 

 extent of the phenomenon, and showed that it pervades animal 

 life from mammals to fishes and through every grade of the 

 insect tribes. I pointed out that the whole series of phe- 

 nomena depend upon the great principle of the utility of every 

 character, upon the need of protection or of concealment by 

 almost all animals, and upon the known fact that no character- 

 istic is so variable as colour, and that therefore concealment 

 has been most easily obtained by colour modification. 



Coming to the subject of " mimicry " I gave a popular 

 acccount of its principle, with numerous illustrations of its 

 existence in all the chief groups of insects, not only in the 

 tropics, but even in our own country. I also showed, I think 

 for the first time, that it occurs among birds in a few well- 

 marked cases, and also in at least one instance among mam- 

 malia, and I explained why we could not expect it to occur 

 more frequently among these higher animals. 



Two other articles which may be just mentioned are those 

 entitled "A Theory of Birds' Nests," and "The Limits of 

 Natural Selection applied to Man." In the first I pointed 

 out the important relation that exists between concealed 

 nests and the bright colours of female birds, leading to con- 

 clusions adverse to Mr. Darwin's theory of colours and orna- 



