xxni] LIFE IN LONDON 407 



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 

 phenomena depend upon the great principle of the utility 

 of every character, upon the need of protection or of con- 

 cealment by almost all animals, and upon the known fact 

 that no character are so variable as colour, and that there- 

 fore concealment has been most easily obtained by colour 

 modification. 



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

 account 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 

 mammalia, 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 

 conclusions adverse to Mr. Darwin's theory of colours and 

 ornaments in the males being the result of female choice. 

 In the other (the last in the volume) I apply Darwin's 

 principle of natural selection, acting solely by means of 

 ■ utilities," to show that certain physical modifications and 

 mental faculties in man could not have been acquired through 

 the preservation of useful variations, because there is some 



