22 PHILOSOPHY OF ZOOLOGY. 



as the defenceless, it may likewise be observed in aqua- 

 tic as well as in terrestrial animals. In reference to acqua- 

 tic animals, we would ask, What protection is afforded to 

 the black guillemot, during the winter, by its mottled plu- 

 mage, or to the little auk, by its Avhite chin, since the whiter 

 their dress, so much the more unlike the dark coloured 

 water of the clouded season in which it is exhibited ? The 

 popular opinion on the subject must be relinquished as un- 

 tenable ; especially as the change of colour from dark to 

 white does not vary, however different the habits or even 

 stations of the animals may be in which it takes place. 



An interesting inquiry yet remains to be made regard- 

 ing the manner in which this change in the colour of the 

 dj-ess is effected. The attention of naturalists has, of late 

 years, been directed to this subject, and several important 

 observations have been made, equally interesting to the phy- 

 siological and systematical zoologist. ; 

 From the belief which is generally entertained, that in 

 hair and feadiers there is no circulation, neither secre- 

 tion nor absorption, a conviction arose in the minds of 

 many naturalists, that the change of colour which takes 

 place in the dress of some animals according to the season, 

 was not the effect of any organical change in the hair or 

 feathers, but accompanied a renewal of the whole. The 

 late George Montagu, Esquire, who had long attended 

 to the characters and habits of the feathered tribes, delivers 

 his opinion on this subject in the following terms : " Some 

 species of birds seem to change their winter and summer 

 feathers, or at least in part ; in some, this is performed by 

 moulting twice a- year, as in the ptarmigan, in others, only 

 additional feathers are thrown out. But we have no con- 

 ception of the feathers changing colour, although we have 

 been informed of such happening in the course of one 



