70 Changes of Fur and Plumage according to the Seasons. 



burrows, where he lives solitarilj-, or at most in families. This rather in- 

 genious explanation may in part be true ; but, unquestionably, it is not 

 all the truth. It is not only in places frequented by man, but likewise in 

 regions which he scarcely ever visits, that scattered and burrowing bea- 

 vers occur. The virgin forests of Louisiana present us with examples, so 

 much the more worthy of notice, from it being impossible to ascribe to 

 any specific difFerencc this remarkable discrepancy in the manners and 

 habits of the beavers of Louisiana and those of Canada. 



M. Desmoulius, to whom we are indebted for having already directed 

 attention to the last-mentioned fact, mentions another, which it is of con- 

 sequence to notice in this place. It is that the Ondatra, so well named 

 by some of the people of North America, the heavier s younger brother, 

 builds a habitation, like it, jn cold regions, and like it also, becomes a 

 burrower in temperate regions. Climate, then, seems here to exercise a 

 marked influence, and if it does not act alone, it must at least be placed 

 side bj' side with the influence produced by the vicinity of man. 



It is in this jioint of view that exact notions respecting the beavers of 

 Norway and Lapland, appear to me to be of such great interest to science. 

 By using every efTort to obtain them, the gentlemen of the expedition will 

 not merely enrich the history of the most remarkable genus in the entire 

 order of gnawers with new facts, but they will contribute to prepare the 

 way for the solution of one of the highest questions in philosophical zoo- 

 logy, the influence of climate and of external circumstances in general on 

 the manners of animals. 



lNote C. — 0)i the Changen of Fur or Plvmayc according to the seasons. 



I have not here pointed out particularly to the attention of the zoolo- 

 gists of the commission, the species which become white or of a lighter 

 colour in the winter. Many observations liave already been made on 

 them by travellers, and I have myself been able to follow the remarkable 

 changes of colour in the Isatis which M. Gaimard sent from Iceland to 

 the menagery of the Museum of Natural History. Here, however, as in 

 every department of zoology, what remains to be done is much greater 

 than what has been already accomplished. 



I shall point out a few subjects for investigation on this head. 



\st, To draw up an exact list of all the species which become perfectly 

 white in winter, and of those which only assume (as appears to be the 

 case with squirrels) lighter tints. 



•1(1, To determine, by exact information, whether there be individuals 

 which remain white .ill the year, and others, on the contrary, which pre- 

 serve the deep-coloured fur or plumage during the winter. 



Zd, To investigate in what order, and in what manner, one colour is 

 substituted for another ; and, in particular, whether it be true that the 

 change of colour takes place in many species without change of feathers 

 or hair, a circumstance which would be contrary to my own observations 

 on the Isatis, but which is admitted as certainly occurring in many nor- 



