CHAPTER XVIII 



COLORS AND MARKINGS OF ANIMALS, AND 

 THEIR USES 



The colors and markings of animals are among the 

 most conspicuous of their external characters, and con- 

 stantly incite us to ask how they are produced and why 

 they are of such great variety. As no more familiar or 

 interesting examples of color patterns can be found than 

 those on the wings of butterflies and moths, \vc can very 

 advantageously use these beautiful insects in beginning 

 the study of animal colors. 



The scales and colors of butterflies' wings. — Catch a 

 few butterflies of different kinds and kill in the killing-bot- 

 tle. With the finger rub lightly one of the wings and 

 note that a fine dust-like substance comes off on the 

 finger-tip, and that at the same time the pattern and color 

 disappear. By gentle steady rubbing with thumb and 

 finger just opposite each other on the upper and lower 

 sides of the wings, a clear, transparent spot may be made. 

 It is evident that tlie color and pattern of the wing de- 

 pends upon its covering of fine particles. 



Rub some of this color-dust from the finger-tip on a 

 glass slide and examine under the microscope. Note that 

 the fine particles are all scale-like in shape and character, 

 each being composed of a tiny short stem and a broader 

 flattened blade which may have the margin of its broad 

 free end even or dentate, that is, showing little teeth or 

 fingers (fig. 220). These tiny scales are hollow and inside 



281 



