338 Review o/HooJcer^s Outlines 



present memoir — prepossessed with Darwin's theory of the diver- 

 sification of species through natural selection — having occasion to 

 revise systematically the materials of the arctic flora, is naturally 

 led to compare the new theory with the facts of the case in this 

 reo"ard ; to see how far the vicissitudes to which it is all but 

 demonstrated that the plants of the northern hemisphere have 

 lono- been subjected, and the modifications and extinctions which 

 he thinks must have ensued under such grave change and perils, 

 during such lapse of time, may serve to explain the actual distribu- 

 tion of arctic species and the remarkable dispersion 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 under- 

 taken. 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 skilfully 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 oc- 

 cupy a circumpolar belt of 10° to 14*^ of latitude. The only 

 abrupt change in the vegetation anywhere along this belt is at 

 Baffin's Bay, the opposite shores of which present, as has been 

 already intimated, an almost purely European flora on the east 

 coast, but a large admixture of purely American species on the 

 west.' 



" Regarded as a whole, the arctic flora is decidedly Scandina- 

 vian ; for Arctic Scandinavia, or Lapland, though a very small 

 tract of land, contains by far the richest arctic flora, amounting to 

 three-fourths of the whole." This would not be very surprising, 

 since this is much the least frigid portion of the zone, and has the 

 highest summer temperature ; but " upwards of three-fifths of the 

 species, and almost all the genera of Arctic Asia and America are 

 likewise Lapponian ;" so that the Scandinavian character pervades 

 the whole.' 



' In the section on the local distribution of plants within the 

 arctic circle. Dr. Hooker shows that there is no close relation dis- 



