SEASONAL CHANGES AND HISTORIES. 155 



sent attainments which marks us as a hurrying, 

 energetic, enterprising people. My own experi- 

 ence has been that studies of precisely the same 

 nature and undertaken under similar external 

 conditions are accompanied by a very different 

 mental state on the two continents. In Europe 

 we are content to plod industriously on, uncon- 

 scious of the need of relaxation ; in America we 

 bend with nervous intensity to our work, and 

 carry the same excitement into the relaxation 

 which such a life inevitably demands. After a 

 long absence in Europe, a keen observer may 

 even be directly conscious of this quickened life. 

 Now to what shall we ascribe such peculiarities 

 in animal life ? Naturally we look to climatic 

 influences, and our attention is first attracted by 

 the well-known fact that if we compare two places 

 in Europe and America having the same mean 

 annual temperature, the extremes of variation 

 will prove much greater on this side of the Atlan- 

 tic. For example, while the mean annual, tem- 

 perature of New York is about the same as that 

 of Frankfort, the summer temperature of the 

 former is that of Rome and its winter that of St. 

 Petersburg. Moreover, the changes from summer 

 to winter and from winter to summer are more 

 immediate in America; or, in other words, the 

 summers and winters are longer by about three 

 weeks. Such long and hot summers are of 



