PLUMAGE IN HEN-BIRDS. 



203 



has clearly remarked, that feathers themselves change 

 colour after having been maturely formed, until late- 

 ly ; and yet it is a well known fact, that many birds 

 have their feathers mottled or grey in summer, and 

 white in winter ; the summer covering being thin 

 and light, the winter thick. The Ptarmigan 

 and Hare are examples. In volume XII. of the 

 Linnean Transactions, there is an interesting paper 

 by the Reverend William Whitear of Sterston, 

 Norfolk, stating, that in some birds, the full grown 

 feathers themselves change colour, without being re- 

 placed by new ones. From this paper it is to be in- 

 ferred, that a change in the colour of the plumage 

 of birds, does not always arise from the change of 

 feathers, but sometimes proceeds from the feathers 

 themselves assuming at one season of the year a 

 different colour from that which they have at ano- 

 ther *. 



It seems to be probable, that birds gaining their 

 winter plumage, have their feathers partly changed in 

 this way. The colour of the feathers, therefore, may 

 be formed at two different times, viz, either when the 

 feathers themselves are growing, or after the feathers 

 have been properly formed ; in the one instance, the 

 colour is co-existent with the growth of the feather ; 

 in the other, superadded to its structure. In the 

 changes of old age, the colour accompanies the 

 growth of the feathers, because it appears with or 



11 Vide. p. 526. Vol. 12. Part ii. Trans. Lin. Soc. 



