author's preface 



of life at all. For this reason I have gone into the subject 

 of colour-adaptations, and especially into that of mimicry, 

 in great detail ; I wished to give the reader a firm foundation 

 of fact from which he could select what suited him when he 

 wished to test by the light of facts the more difficult problems 

 discussed in the book. 



In conclusion, I wish to thank all those who have given 

 me assistance in one way or other in this work : my former 

 assistant and friend Professor V. Hacker in Stuttgart, my 

 pupils and fellow workers Dr. Gunther and Dr. Petrunkewitsch, 

 and the publisher, who has met my wishes in the most 

 amiable manner. 



Freiburg-i-Br., 

 February 20, 1902. 



