CONDITIONS AFFECTING DISTRIBUTION. 61 



number of these groups ; but in certain places they present 

 themselves in a number of species and of individual plants 

 giving to the vegetation of the place its particular 

 character. 



' When on a map there are marked the districts in 

 which the different groups of plants principally predo- 

 minate we discover that with the one exception of the 

 most common species the development of groups is not 

 continuous. The Arctic flora only shows itself it its 

 characteristic form, here and there, in scattered colonies, 

 separated by extensive species in which the Sub-Arctic 

 predominates. The boreal flora also presents itself 

 scattered over the low-lying districts of the eastern portion 

 of the country around the Christiania fiord, and the Miosen 

 lake, then at a distance to the west, beyond the Lang- 

 fjelde, near the inland branches of the fiords of the 

 western littoral, and lastly on the low lying lands on the 

 north of the country. On the intermediate low lying coasts 

 the Atlantic flora reigns. This is equally with the others 

 isolated by the greater part of the Atlantic species find- 

 ing themselves in the south-west portion of Sweden, but 

 not around the Christiania Fiord. Some which have only 

 been found on the west coast of Norway, find themselves 

 again only on the west and the south coast of the German 

 Ocean/ 



Dr Broch goes on to say : ' The present flora of 

 Norway cannot have always existed there. At a 

 geological period, which is not very distant, the pen- 

 insula, up to the most remote plateaux of the land, was 

 covered with a bed of ice and snow, overlooked only by 

 the bare summits of some few of the most elevated moun- 

 tains. At this time the trees, shrubs, arid plants, which 

 now beautify the valleys could not have lived. They 

 existed, however, anterior to the so-called glacial period 

 on other parts of the terrestrial globe. They have been 

 found in a fossil state in beds of coal deposited prior to 

 this period. It is an immigration from other countries 



