4 PREFACE 



commend itself to me if I had anything to do with the 

 appointment' 



A very natural inquiry may be raised as to why a 

 collection of Insects^ above all other animals, should be 

 so especially valuable for the elucidation of the larger 

 problems which deal, not only with the species of a single 

 group, but with every one of the innumerable and 

 infinitely varied forms, vegetable no less than animal, 

 in which life manifests itself. The answer is to be found 

 in the large number of offspring produced by each pair 

 of Insects, and the rapidity with which the generations 

 succeed each other, many cycles being completed in a 

 single year in warm countries ; in the severity of the 

 struggle for life which prevents this remarkable rate of 

 multiplication from becoming the cause of any progressive 

 increase in the number of individuals ; and finally in the 

 character of the struggle itself, which is precisely of that 

 highly specialized kind between the keen senses and 

 activities of enemies and the means of concealment or 

 other modes of defence of their Insect prey, which leads 

 by action and answering reaction to a progressive raising 

 of the standard in both pursuer and pursued. This is 

 why it is that Insects mean so much to the naturalist 

 or the philosopher who desires to look beneath the surface 

 for the forces which have moulded existing forms of life 

 out of earlier and very different forms. The wings of 

 butterflies, it has been said^ 'serve as a tablet on which 



^ H. W. Bates, quoted by A. R. Wallace in ' Natural Selection,' London, 

 1875, p. 132. A more extended quotation is much to the point. H. W. Bates 

 was writing in ' The Naturalist on the Amazons ' (London, pp. 347, 348 of 

 the 1879 edition), on the abundance and variety of the butterflies at Ega on 

 the Upper Amazons. (A few of the actual specimens captured by him in this 

 locality are in the Hope Collection.) ' I paid especial attention to them,' he 

 writes, ' having found that this tribe was better adapted than almost any 



