Color and Pattern and their Uses 
611 
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 
