234 PROCEEDINGS OF THE AMERICAN ACADEMY 



XIT. 



ON THE COLOE AND THE PATTERN OF INSECTS. 



By Dr. H. A. Hagen. 



Presented April 12, 1882, 



" Probably there is scarcely a dash of color on the wing or body of 

 an insect of which the choice would be quite arbitrary, or which 

 might not affect its duration for thousands of years." These words 

 were written by Sir Charles Lyell in a letter to Sir John Herschel in 

 1836.* This letter, which is a real treasure of thought, asserts 

 clearly that the writer assumes " such contrivances must sometimes 

 be made, and such relations predetermined between species," for the 

 protection of their existence. 



Though it has been accepted generally that certain colors and 

 patterns of insects might be a protection against enemies, these inter- 

 esting facts have been mentioned only occasionally, and a general 

 review is still a desideratum. Professor Weismann t has given a 

 very elaborate paper on the origin of the pattern of caterpillars. The 

 paper, as stated in the preface, intends an examination of the pattern 

 strictly for the purpose of finding out whether all patterns can be 

 accepted as the consequences of selection and adaptation, and as pro- 

 duced in a purely mechanical manner, or whether some unknown 

 power has to be accepted in part or entirely to explain the pattern. 

 The writer reaches the conclusion that the latter is not the case, and 

 that the known principles of selection and adajitation explain the dif- 

 ferent patterns. The choice of caterpillars was made purposely to 



* Life, Letters, and Journals of Sir Charles Lyell, Bart., London, 1881, vol. i. 

 p. 4G9; Nature, No. G33, Dec. 15, 1871, p. 147. 



t Dr. A. Weismann, Studien zur Descendenz-Tlicorie, Leipzig, 1875, vol. i. ; 

 1876, vol. ii. Die Entstehung der Zeiclmung bei den Suhmettorlings Kaupcn. 



