292 Ml-. G. A. K. Marshall 07i 



1. INTRODUCTION. 



A. By Guy A. K. Marshall. 



The observations and experiments which form the 

 groundwork of the present memoir were originally under- 

 taken by mo at the instance of Prof. Poulton, and such 

 interest as they may possess is largely due to his valuable 

 suggestions and advice. Moreover he has been good 

 enough to undertake the entire clerical w^ork in connec- 

 tion with the publication of the paper, and he alone is 

 responsible for the numerous excellent plates with which 

 it is illustrated. The utility of experiments such as here 

 recorded depends almost entirely upon the manner in 

 which the results may be treated. The mere accumula- 

 tion of facts of this kind has little real value, unless these 

 facts are properly classified and co-ordinated, and their 

 bearing upon current theories adequately considered and 

 discussed. This portion of the work has been left almost 

 entirely in Prof. Poulton's hands, and I feel that I am 

 fortunate in having obtained his hearty co-operation ; for 

 his wide experience in this particular line of research 

 insures a thorough treatment of the subject. 



In carrying out the experiments I have always en- 

 deavoured, so far as in me lay, to record the results as 

 impartially as possible. But on reviewing my experiences 

 as a whole I cannot escape the conclusion that they lend 

 very strong support to the theories of Mimicry and 

 Warning Colours as enunciated by Bates, Fritz Mliller, 

 and Wallace ; I feel convinced that were naturalists more 

 ready to carry out extensive experiments of this nature 

 there would be much less of the prevalent a 'jyriori criti- 

 cism of these valuable theories which throw light upon a 

 vast number of facts which must otherwise remain for us 

 mere meaningless coincidences. It is especially important 

 that experiments should be made by as many different 

 observers as possible, for in this way alone can the errors 

 due to unavoidable personal bias be eliminated ; and if 

 the present ]uiblication only has the effect oj inducing 

 other entomologists in South Africa, or elsewhere, to turn 

 their attention to the interesting problems involved, it 

 will have fully served its purpose. 



G. A. K. M. 



