A SQUIRRELS NEST. 91 



It is odd, too, how general among the rodents is this 

 instinct of laying-by supplies for the winter, due, no 

 doubt, in part to the exceptionally imperishable nature 

 of their chief foodstuffs (for nuts, grains, and roots do 

 not decay quickly, like fruits or meat), and in part to the 

 usual close similarity in their surroundings and mode of 

 life. We can hardly regard it as a habit derived from a 

 single common ancestor, because it appears so sporadic- 

 ally, and so many related species are wholly wanting in 

 it. Most probably it has been independently evolved in 

 the squirrel, the harvest-mouse, the rat, the field-mouse, 

 and the beaver, from the fact that in each group alike 

 those who manifested it most would always best survive 

 through the chilly and foodless northern winters. On 

 the other hand, the storing instinct is sometimes replaced 

 among allied animals by other instincts almost equally 

 remarkable : as in the case of the dormouse, who gets 

 over the same difficulty by fattening himself inordinately 

 during the summer, and then sleeping away the winter 

 so as only to use up the irreducible minimum of food- 

 stuffs in the absolutely indispensable vital actions of the 

 heart and lungs. From the point of view of mere sur- 

 vival, it would matter little whether any particular group 

 happened to fall into the one practice or the other. It 

 is very noticeable, however, that while the sleepiness of 

 the dormouse has fostered, or at least has not militated 

 against, a stupidity as great as that of the guinea-pig or 

 the tame rabbit, the more active and provident habits of 

 the squirrel and the beaver have fostered an amount of 

 intelligence extremely rare among rodents, or, indeed, 

 among animals generally. I once kept a tame squirrel 

 for some months, not in a wretched little tread-mill cage, 



