26 PHILOSOPHY OF ZOOLOGY. 



organs, What prevents us from supposing that similar 

 changes take place in the feathers ? But even in the case 

 of birds, we have before us an example as convincing as the 

 ermine already mentioned. It is a specimen of the little 

 auk (Alca atle), which was shot in Zetland in the end of 

 February 1810. The chin is still in its winter dress of 

 white, but the feathers on the lower part of the throat have 

 assumed a dusky hue. Both the shafts and webs have be- 

 come of a blackish grey colour at the base and in the centre, 

 while the extremities of both still continue white. The 

 change from black to white is here effected by passing 

 through grey. If we suppose that in this bird the changes 

 of the colour of the plumage are accomplished by moult- 

 ing, or a change of feathers, we must admit the existence 

 of three such moultings in the course of the year one 

 by which the white winter dress is produced, another for 

 the dusky spring dress, and a third for the black garb of 

 summer. It is surely unnecessary to point out any other 

 examples in support of our opinion on this subject. We 

 have followed nature, and our conclusions appear to be jus- 

 tified by the appearances which we have described *." 



Since the preceding observations were communicated to 

 the public, Professor JAMESON has obligingly pointed out 

 to me the following passage in CAUTWRIGHT'S Journal of 

 Transactions on the Coast of Labrador (3 vols. 4to. Newark 

 1792), vol. i. p. 278, as containing an expression of the 

 same opinion which I had formed upon the subject. " 28th 

 September 1773. This morning I took a walk upon the 



* The Reverend Mr WHITEAR, in his " Remarks on the Changes of the 

 Plumage of Birds," in Linn. Trans, vol. xii. p. 524, read April 6. 1819, 

 has recorded several striking facts, observed in the plumage of "the mallard, 

 chaffinch, and some other birds, which corroborate the opinion advanced 

 above. 



