96 THE COLOURS OF ANIMALS 



is retained from December till the end of April. The 

 appearance of the back and sides in summer is ' glis- 

 tening fawn-colour interspersed with black, especially 

 over the vertebral ridge.' The colour is conferred by 

 long thick hairs (the pile) covering a woolly under- 

 growth of a slaty colour. 



Early in October the first changes appear ; the 

 whiskers become white at the tip or in some part of 

 the shaft, and a few of the longer hairs on the back 

 also become white at the tip or throughout. At this 

 time there is no addition to the summer coat, only a 

 change in the colour of existing hairs. The changes 

 advance during November, and on separating the fur 

 a new growth of stiff white hairs is seen over the sides 

 and back : these grow rapidly, while the long hairs of 

 the summer coat also grow and become white very 

 quickly as soon as the new hairs appear on the surface. 

 * The shaft of the hair of the new growth is invariably 

 white, a circumstance which renders it easily distin- 

 guished from the autumnal hair in process of change.' 

 This change is most frequent at the tip, proceeding 

 downwards, but it sometimes begins in the middle, 

 and occasionally at the base. ' The whiskers, which 

 apparently do not lengthen but merely alter in colour, 

 will demonstrate each variety. 



' Thus the whiter hue would appear to be brought 

 about by a change of colour in the pile of the autumnal 

 coat, combined with a new hybernal white crop, the 

 latter undoubtedly playing no small part in the 



