Form and Color in Nature. 255 



many other insects originally acquired brilliant colors, more 

 or less resembling those of the flowers which they chiefly 

 visited, as a protection from the birds by which they were 

 sought. And as one part of the evidence in this case it is 

 noteworthy that certain butterflies which have acquired a 

 nauseous taste, and are therefore not sought after, are very 

 marked in their coloring, and make no effort to conceal them- 

 selves. And as an instance of protective mimicry it is to be 

 added that the females of certain other species have sought 

 or found protection by closely imitating the marking of these, 

 which differs greatly from the type to which they belong. 

 This is a form of mimicry of which there are many in- 

 stances. Then there is the imitation of vegetable colors 

 and forms in many inhabitants of trees and smaller plants, 

 in caterpillars and in larger creatures as well imitations so 

 close that even the eye of a practiced naturalist is some- 

 times deceived. And the colors frequently change accord- 

 ing to the season. But, most marvelous of all, numerous 

 careful experiments made upon larvae by Mr. Poulton and 

 others have shown that their color can actually be altered 

 from day to day by changing the colors surrounding them. 

 These changes occur in the individual creature experi- 

 mented upon, and therefore differ from the cases of color 

 acquired through development, with which mainly I have 

 been dealing. Their method of production is one of the 

 many items in the study of natural history which require a 

 vast deal more investigation than they have yet had. 



The case of the chameleon is a peculiar one. This lizard 

 has long been a synonym for variability in color, and it is 

 only within a few years that it has been discovered that it 

 has two or more sets of pigment cells, so placed that they 

 can be projected in turn and at different angles to the light, 

 and that it is by the use of these that it can totally change 

 its appearance at will. 



In mammalia the colors are generally more subdued than 

 they are in the case of birds and insects, and there is some 

 doubt whether their sense of color is quite so strong. ^ The 

 color is frequently protective, as shown, for instance, in the 

 brown or tawny tints of those animals which live upon 

 sandy deserts, the tendency to stripes found among those 

 living among reeds, etc. These general characteristics are 

 modified in individual cases, as they are among nearly all 

 species in all families, by what are called recognition mark- 

 ings, which are supposed to have been acquired or retained 



