Remarks about the Relations 
of the Floras of the Northern Atlantic, the Polar Sea, 
and the Northern Pacific. 
By 
Herman G. Simmons. 
Lund, Sweden. 
It is a fact, known already for a long time, tliat a great 
many species of the northern liemisphere have a circumpolar 
distribution. An interpretation of this circnmstance became 
possible first when geologists hacl 'come to know the Glacial 
Period and its effects. After similar views had been advanced 
in the works of Porbes, Lyell and otkers, Darwin in 
Origin of species (12) shows how the iceage must have driven 
the old tertiary plants of the districts aronnd the pole, or their 
descendants, from the territories they once occnpied, southwards 
into the continents of onr time, where they fonnd an asylnm during 
the glaciation. At the time when the ice again melted away 
they began slowly to wander back, interspersed with alpine 
elements from the districts where they had survived the iceage. 
At Ihe same time they also left tribes in their temporary 
homesteads, which contributed to a new colonization of the 
Southern mountains. In such a manner the great number of 
, circumpolar species is accounted for and likewise tkat contingent 
of species, which every arctic district has in common with the 
alpine region of the mountains sonth of it, bnt not with other 
districts. 
This theory, further developed by Sir Joseph Hooker in 
his Outlines of distribntion of arctic plants (24) and by later 
authors, is now universally adopted and donbtless well founded. 
Still it has as yet mostly been brought to bear onlv upon the 
higher plants, or at most upon the landvegetation as a whole. 
As far as marine algae are concerned only few writers have 
tried to rnake use of this point of view for the exphcation of 
the present distribution of species and genera. However, some 
suggestions are made by Kjellman- (30) and Reinke (40). 
