ERMINE WEASEL. 199 



basal or brown part of the tail and on the toes that the 

 white first makes its appearance ; and after this, the white 

 of the belly extends upwards on the animal's sides, thus 

 destroying the regularity of the line where the brown and 

 white meet; about the same time the limbs become 

 powdered with white. A more advanced stage shows the 

 limbs and root of the tail white, and the brown of the 

 back reduced to a narrow stripe, excepting on the rump, 

 which, with the head and hind neck, is the latest to 

 change ; and, in fact, these parts rarely become quite 

 white in this country. 



The following statement of an experiment recorded in 

 the account of the former voyage of Captain Ross to the 

 Polar regions, offers an interesting confirmation of the 

 theory above offered, though the animal which was the 

 subject of it belonged to a very different group. It was 

 the Hudson's Bay Lemming : 



" As it retained its summer fur, I was induced to try 

 the effect of exposing it to the winter temperature. It 

 was accordingly placed on deck in a cage on the 1st of 

 February ; and next morning, after having been exposed 

 to a temperature of 30 below zero, the fur on the cheeks 

 and a patch on each shoulder had become perfectly white. 

 On the following day the patches on the shoulders had 

 extended considerably, and the posterior part of the body 

 and flanks had turned to a dirty white. At the end of a 

 week it was entirely white, with the exception of a dark 

 band across the shoulders, prolonged posteriorly down to 

 the middle of the back." It is unnecessary to pursue 

 the details of this cruel but conclusive experiment 

 further ; it obviously proves that a low temperature 

 alone is sufficient to blanch the fur in such animals as are 

 susceptible of such a change. It also clearly shows that 

 the view which we have taken of the mode in which this 



