LEPUS 303 



feathers of Lagopus albus, both of which are thus shown to be 

 living structures. He held that the phenomenon is one of a 

 general kind, which would be found present in other whitening 

 animals such as ermines and mountain squirrels. Metchnikoff 

 thus proved that the view frequently expressed that whiteness 

 might be due to bubbles of air entangled in the structure of the 

 hairs is erroneous. Trouessart {Compt. rend, des stances Soc. 

 Biol., Ix., loth February 1906, 271) corroborated Metchnikoff 

 as a result of the examination of ermines and squirrels. He 

 found that after loss of pigment the central medulla of a hair 

 becomes desiccated, retracts, and dies. 



The cycle of coat and colour changes undergone in a cold 

 country of comparatively regular climate is different from that 

 which prevails in the milder but uncertain weather of Britain, 

 and this fact accounts for much discrepancy between reports 

 from various localities. As stated above, the existence of the 

 spring moult is undoubted (Barrett- Hamilton, Proc. Zool. Soc, 

 London, i6th May 1899, 598), but careful search for an autumn 

 moult is often unavailing. A Scottish Hare kept alive at 

 Cambridge during the autumn of 1899 by Barcroft, had turned 

 almost completely white by January 1900 {Proc. Roy. Irish 

 Acad., xxiv., B, nth May 1903, 303-314). But, although it 

 was constantly under observation in a specially constructed 

 cage, no trace of depilation was detected. 



I have since found the autumnal moult occurring irregularly 

 in wild specimens of the Irish Hare, but at the same time a 

 number of Scottish Hares were examined in different localities 

 on my behalf, and there was no shedding of hair, so that 

 observation supports MacGillivray's view, that in Britain both 

 moult and withdrawal of pigment may exist side by side. The 

 change of pelage is as irregular as the climate in which the 

 animals live, and is so susceptible to the influence of the 

 weather that, as shown by MacGillivray, although the great 

 annual casting takes place in the spring, there may be a renewal 

 at any season or in any month. 



The autumnal depigmentation varies with the locality and 

 the climate. In a cold country of regular seasons it comes on 

 early and is rapidly completed. In a temperate country of 

 irregular weather it begins gradually, lasts a comparatively 



