926 Till-: HUTTKRFUKS Ol" NKW KXCLAXD. 



tlicro is no revi-rsal of tlie nilo : among all the hutterflit's properly com- 

 parable ou the two continents, thi-re is no single iiistunrc where ihe 

 European butterfly has more brooch than the American. 



Tliis result of a comi)arison of the annual histories of similar European 

 and American butterflies thus furnishes but another instance of that inten- 

 sity which seems to characterize all life in America. The expenditure of 

 nervous and vital energy, against which physicians vainly inveigh, which 

 superannuates our mercliants, lawyers, clergymen, and other professional 

 men, is not induced by the simple passion for gain, place, power or knowl- 

 edge, but by an uncontrollable restlessness, a constant dissatisfaction with 

 present attainments, which marks us as a hurrying, energetic, enterprising 

 people. My own experience in the preparation of the present work has 

 been that studies of precisely the same nature and undertaken under sim- 

 ilar external conditions are accompanied by a very diflFerent mental state 

 on the two continents. In Europe we arc content to plod industriously 

 on, unconscious of the need of relaxation ; in America we bend with ner- 

 vous intensity to our work, and carry the same excitement into the relaxa- 

 tion which such a life inevitably demands. After a long absence in 

 Europe, a keen observer may even be directly conscious of this quick- 

 ened life. 



Now to what shall we ascribe such peculiarities in animal life ? Nat- 

 urally we look to climatic influences, and our attention is first attracted by 

 the well known fact tliat 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 Atlantic. For example, while the 

 mean annual temperature 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 woi'ds, the summers and winters are longer by about three weeks. 

 Such long and hot summers are of course favorable to the multiplication 

 of broods in butterflies whose historj' allows a repetition of the same cycle 

 more than once a year ; the length of the winter is of slight consequence, 

 as long as the insects can survive it ; and it can have no influence upon 

 the number of broods, unless there be species (of which we know nothing) 

 able to resist a cold winter only in certain stages of existence, and a mul- 

 tiplication of whose broods might require some pliability in this respect. 

 Not only, too, are our stmimers longer and hotter, but they enjoy a 

 marked preponderance of sunshine, as compared with European summers ; 

 and this alone would almost seem capable of jn-oducing the variation we 

 have noticed in the number of broods. 



In an extremely interesting article (Actes Soc. lielv. sc, 18.53, 138- 

 150) on the eflPect of our climate on manners and customs, written bv tlie 



