104 JOURNAL AND PROCEEDINGS 



changes cannot be better described than by a quotation from 

 the same authority. " Where the chief portion of this great 

 northern flora originated, and whether it may be best termed 

 Scandinavian, or North Asiatic or Caucasian, is a question for 

 the determining of which we have little or no data. It is how- 

 ever one of the most ancient and widest spread, having at 

 different times travelled over a great part of the Globe. 



Recent researches have shown that the plants belonging 

 to this flora extended far north during the warmer pre-glacial 

 times, and that it must have been slowly driven southward as 

 the glacial Epoch came on, and either then, or at some one or 

 other periods, liaVe been for a time continuous in two lines, at 

 least, into the Southern hemisphere, for it has left traces 

 easily discernable, especially in its herbaceous and mountain 

 forms in the mountains of tropical Asia and to the Abyssinian 

 mountains of Africa, and down the Andes to the extreme 

 south of America where it is still luxuriant. In all these 

 migrations, while retaining a general identy, the flora must 

 have undergone continuous changes, losing species as their 

 habitations became unfit for them, and gradually forming new 

 ones when favored by long continued isolation or other 

 requisite conditions." 



The only other remark I would make about this division 

 of our subject is that this flora has undergone a sort of special- 

 ization into three secondary floras, but I shall only speak of 

 one of these, the most interesting of the three — It is usually 

 termed the Arctic Alpine flora, consisting chiefly of plants of 

 small stature, slow growth and limited means of dispersion, 

 but compensated by long lines and great powers of endurance. 

 It is interesting because it reduces the divergence of the Old 

 and New World division to a minimum, and more especially 

 on account of the great interest which attaches to the problem 

 of its scattered Alpine outliers. 



With regard to the first point Hooker has found that 

 estimating the whole Arctic flora at 762 species, Arctic East 

 America ^ possessed 379, of which 269 were common to 

 Scandinavia. Of the whole flora 616 species are found in 



