76 ANIMAL COLORATION. 



Scotland ; occasionally the change occurs in the Midlands, 

 and white stoats have been recorded from Cornwall, and from 

 Gloucestershire even during a mild winter. The accompany- 

 ing woodcuts (figs. 1, 2) illustrate the winter dress of some 

 of the animals referred to in the text ; the Arctic fox (fig. 1) 

 is shown both in summer and winter dress. 



The actual mode of the change in the colour of the fur has 

 been carefully worked out by Mr. Welch* for Lepus americanus. 

 The change in the summer coat is accomplished without the 

 shedding of hair ; but there is a new growth of white hair. 

 Naturally the winter coat is thicker than the summer coat- 

 Besides the increase in the thickness of the fur produced by 

 the growth of new hairs, the coloured hairs change their colour 

 and become blanched. This blanching usually commences at 

 the tip, and does not always involve the whole of the shaft. 

 The entire change occupies three months ; it begins about 

 the first week in October, and is completed by the last week 

 of December. 



The change is more rapid in other animals. In a lemming 

 Sir John Ross found the change to take place in a week. 



It is thought that it is the change of temperature whicli 

 produces the change in the hair ; but it would be very im- 

 portant to ascertain whether this is really the case, and, if so. 

 what are the limits of cold within which the change will or 

 will not occur. 



The experiment of Sir John Ross upon the lemming appears 

 almost to settle the point. The animal was kept in the cabin 

 through the winter, and first exposed on deck on February 

 1st ; on the next day it had several white patches, and, as 

 already stated, became white in a week, but the creature died 

 a few days afterwards. On the other hand, the whitening of 



* Proc. Zool Soc., 18G9. 



