70 ANIMAL COLOEATION. 



natural selection had, so to speak, ceased to encourage its 

 production, this would necessarily iuiply the first formation of 

 pigment under the influence of natural selection ; whereas 

 those who advocate the important effects which natural 

 selection has caused in the patterns of coloration admit that 

 they do not explain by this theory the origin of the pigment. 

 It must be there before it can be acted upon, and modified in 

 this or that direction according to the needs of the animal. 



Seasonal Change in Colour. 



A change to white at the approach of winter is well known 

 to occur commonly among Arctic animals. But it is not so 

 well known — or, at least, so much stress has not been laid upon 

 the fact — that many animals which inhabit more temperate 

 climates have a winter and a summer dress. 



It will be well to commence with a few instances of the 

 latter, before proceeding to discuss the nature and meaning of 

 the complete change to white which occurs in certain Arctic 

 mammalia. In the Manchurian deer (Cei'cus mantchuricus) 

 the summer dress is a yellowish-brown with white spots ; in 

 the winter the colour of the hair becomes much darker, and 

 the white spots are barely visible at all, except just on the back 

 above the shoulders. A quite similar change takes place in 

 the Japanese deer, but a conspicuous white patch by the tail is 

 nearly as evident in winter as in summer. 



In other species of deer there is no such alternation between 

 a spotted and an unspotted condition. In Cen:us, ducaucelli 

 for example, Mr. Sclater * describes the winter coat as of " a 

 dullish brown, which, however, changes in summer into a 



* In a monograph of the Deer in the Zoological Society's Gardens 

 {Trans. Zoul. Soc, vol. vii.), from which paper the other facts about deer 

 are drawn. 



