Mimetic Patterns to the Original Form. 77 



my conviction, formed after much deliberation, of the 

 gradual and natural character of these complicated 

 changes, and of the absence of any violent or arbitrary 

 element in their process of development. Whether 

 the explanations here suggested are true and adequate, 

 can in most instances only be decided by observation in 

 the field ; and it is much to be desired that travellers and 

 residents in countries where these and similar phenomena 

 occur should carefully record all facts relating to the 

 habits, postures, modes and times of flight, prevalence, 

 seasonal occurrence and exact distribution of the various 

 species that come under their observation. 



There is also need of such experimental evidence as to 

 the means of defence adopted by these forms as can only 

 be satisfactorily obtained in the midst of their natural 

 surroundings. Meanwhile, it must suffice to point out 

 the conclusion towards which the only facts available 

 appear to lead, while the actual verification by observa- 

 tion and experiment must perforce be left to those whose 

 opportunities enable them to apply these final tests to the 

 subjects of enquiry. 



My best thanks are due to Prof. Poulton, F.R.S., for 

 much encouragement and many facilities for work. The 

 figures were drawn, by his permission, from specimens in 

 the Hope Collection at Oxford. 



