1906] Animal Coloration. 159 



excitement. Seasonal colors are of a different character. Thus 

 the stoat, Alpine hare, Arctic fox, &c, change from the sombre 

 summer hues to snowy white, the tail or ear-tips remaining black 

 in some instances, The beetle, Carabus auratus, is dusky in 

 winter, but green in summer, while the spring and summer broods 

 of one butterfly, a Vanessa, are in great contrast as regards color, 

 &c. The winter pupa emerges in spring as Vanessa levana, while 

 the second brood emerging in summer is distinguished as Vanessa 

 prorsa, the contrast in coloration being attributed mainly to 

 temperature, just as melanism, or the appearance of dark forms 

 of certain species is said to be due to temperature and moisture. 



If animals have appreciation of colors as is certainly the case, 

 there are types which must be classed as "Aesthetic" implying 

 delight in or preference for certain tints and arrangements of 

 color. 



Lord Avebury proved that bees prefer blue colors and Pro- 

 fessor Poulton has found other instances. Darwin satisfied him- 

 self that female birds prefer brilliantly tinted male birds but this 

 ' ' sex selection " is only a particular form of ' aesthetic preference. " 

 Aesthetic coloration affords some of the most enchanting examples 

 known to the naturalist, and perhaps the acme is reached in the 

 gorgeous male Nicobar pigeon, a native of Java and Sumatra, 

 which glitters in the serried hues of emerald, gold and metallic 

 blue, surpassing the wondrous colors of the parrots and birds of 

 Paradise. 



Parasitic colors are due to parasitism, and are usually sombre 

 for protection's sake like some of the bird ticks ; but the horse and 

 deer ticks (Trichodectes) and others are striped down the dorsum. 

 Many parasites especially entoparasites are opaque white, having 

 lost all coloration, from their mode of life in the interior of their hosts. 

 Their surroundings are dark like the cave animals. En- 

 vironmental colors are a form of mimicry and ensure the safety 

 of the possessors. They may be classed as passive or procrpytic, 

 the various flounders and shrimps, which most accurately resemble 

 the sandy bottom, are examples. Others are active or anticryptic 

 colors like those of the tiger, which is concealed by its stripes and 

 thus able to spring unobserved upon its prey. Spiders and many 

 predaceous creatures show anticryptic coloration. 



