Scientifio Intelligence. 



the author of the present 

 I with Darwin's theory of the diversification of species 



;tic flora, is naturally led to compare the new theory with the 

 ■ '3 regard ; to see how far the vicissitudes to which it is 

 at the plants of the northern hemisphere have long been 



ensued under such grave changes and perils, during such lapse of time, may 

 serve to explain the actual distribution of arctic species and the remarkable dis- 

 persion of many of them. That the enquiry is a legitimate and a hopeful one 

 ■we must all agree, whether we favor Darwinian hypotheses or not. How well 

 it works in the present trial we could not venture to pronounce without a far 

 more critical examination than could now be undertaken. But there are good 

 reasons for the opinion that this is just the ground upon which the elements of 

 the new hypothesis figure to the best advantage. 



The mass of facts, so patiently and skillfully collected and digested in this 

 essay, have a high and positive value, irrespective of all theoretical views. 

 We cannot undertake to offer an abstract, but may note here and there a point 

 of interest The flowering plants which have been collected within the arctic 

 circle number 762, viz. : 214 Monocotyledons, and 548 Dicotyledons. They 

 occupy a circumpolar belt of 10° to 14° of latitude. The only abrupt change 

 in the vficrptatinn anvwhere along this belt is at Baffin's Bay, the opposite 

 :, as has been already intimated, an almost purely bu- 

 large admixture of purely American 



Hooker shows 



nial lines (whether annual or monthly) and the amount of vegetation, beyj ^ 



greaf southern bend in Asfa'S its Schnesstl Lapkndj with an equally 

 great northern bend there, of the annual isotherm of SS'^. Yet " tao - • ' 

 isotherm bends northwards in passini^ from Eastern America to Grooi^'. 



of Iceland, which is mhch poorer in species than those parts of Laj>li: 

 southward of which it passes." A glance at the supposed former stat' ■ 

 would suggest the explanation of all that is anomalous here. 

 "The June is. - - 



a far greater diversity »' 

 lan in the Eastern United 



