Color and Pattern and their Uses 6 1 1 



ill taste or a sting when he attacks an insect of certain type or pattern. This 

 requirement of relative abundance of mimicker and mimicked seems actu- 

 ally met, as proved by observation. In some cases only females of a species 

 indulge in mimicry, the males being unmodified. This is explained on the 

 ground of the particular necessity for protection of the egg-laden, heavy- 

 flying, and long-lived and hence more exposed females, as compared with 

 the lighter, swifter, shorter-lived males. 



It has been found that individuals of a single species may mimic several 

 different species of defended insects, this polymorphism of pattern existing 

 in different localities, or indeed in a single one. Marshall believes that the 

 seasonal polychromatism of certain butterfly species is associated with the 

 mimicry of certain defended butterflies of different species, these different 

 species appearing at different times of the year. 



Criticisms and general consideration of the foregoing hypotheses of 

 color use. It is needless to say that such hypotheses and theories of the 

 utility of color and pattern have been subjected to much criticism, both 

 adverse and favorable. The necessity for limiting results within the working 

 range of efficient causes has been the soundest basis, to my mind, for the 

 adverse criticism of the theories of special protective resemblance, warning 

 colors, and mimicry. Until recently most of the observations on which the 

 theories are based have been simply observations proving the existence of 

 remarkable similarities in appearance or equally striking contrasts and 

 bizarrerie. The usefulness of these similarities and contrasts had been 

 deduced logically, but not proved experimentally nor by direct observation. 

 In recent years, however, a much sounder basis for these theories has been 

 laid by experimental work. There is now on record a large amount of strong 

 evidence for the validity of the hypothesis of mimicry. Certainly no other 

 hypothesis of equal validity with those of protective resemblance and mimi- 

 cry has been proposed to explain the numerous striking cases of similarity 

 and the significant conditions of life accompanying the existence of these 

 cases, which have been recorded as the result of much laborious and indefati- 

 gable study by certain naturalists. 



Plateau and Wheeler have tasted so-called inedible or distasteful insects 

 and found nothing particularly disagreeable about them. But as Poulton 

 suggests, the question is not as to the palate of Plateau and Wheeler nor of 

 any men: it concerns the tastes of birds, lizards, etc. Better evidence is 

 that afforded by actual observation of feeding birds and lizards; of experi- 

 mental offering under natural conditions of alleged distasteful insects to 

 their natural enemies. Marshall's observations and experiments on the 

 point are suggestive and undoubtedly reliable. Much more work of the 

 same kind is needed. 



The efficient cause for bringing color and pattern up to such a high 



