126 REVIEWS. 



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 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 j^ronounce 

 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, irre- 

 spective of all theoretical views. We cannot undertake to 

 offer an abstract, but may note here and there a poinl of in- 

 terest. The flowering plants which have been collected 

 within the arctic circle number 762, namely, 214 Monocoty- 

 ledons and 548 Dicotyledons. They occupy 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 in- 

 timated, an almost purely European flora on the east coast, 

 but a large admixture of purely American species on the 

 west. 



" Eegarded as a whole, the arctic flora is decidedly Scan- 

 dinavian ; 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 por- 

 tion 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 Lap- 

 poniau ; " so that the Scandinavian character pervades the 

 whole. 



In the section on the local distribution of plants \\athin the 

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

 discoverable between the isothermal lines (whether annual or 

 monthly) and the amount of vegetation, beyond the general fact 

 that the scantiness of the Siberian flora is associated with a 



