vii.] THE PEE-GLACIAL FLORA. 165 



beyond the Ural Mountains, and in America, save in 

 Labrador, where the common ling, an older and less 

 specialised form, exists. You must consider, too, the 

 plants common to the Azores, Portugal, the West of 

 England, Ireland, and the "Western Hebrides. In so 

 doing young naturalists will at least find proofs of a 

 change in the distribution of land and water, which 

 will utterly astound them when they face it for the 

 first time. 



As for the Northern flora, the question whence it 

 came is puzzling enough. It seems difficult to conceive 

 how any plants could have survived when Scotland 

 was an archipelago in the same ice-covered condition 

 as Greenland is now ; and we have no proof that there 

 existed after the glacial epoch any northern continent 

 from which the plants and animals could have come 

 back to us. The species of plants and animals common 

 to Britain, Scandinavia, and North America, must 

 have spread in pre- glacial times when a continent 

 joining them did exist. 



But some light has been thrown on this question 

 by an article, as charming as it is able, on "The 

 Physics of the Arctic Ice/' by Dr. Brown of Campster. 

 You will find it in the " Quarterly Journal of the Geo- 

 logical Society" for February, 1870. He shows there 

 that even in Greenland peaks and crags are left free 

 enough from ice to support a vegetation of between 

 three hundred or four hundred species of flowering 

 plants ; and, therefore, he well says, we must be careful 

 to avoid concluding that the plant and animal life on 

 the dreary shores or mountain-tops of the old glacial 

 Scotland was poor. The same would hold good of our 

 mountains ; and, if so, we may look with respect, even 



