687 



view: 1) that the biological conditions in the currents, which lead 

 to the Færoes, are very variable and different from those at the 

 Færoese coasts, 2) that marine algæ are very sensitive to changes 

 of temperature and salinity, and also, 3) that the white light of the 

 surface may have a destructive influence especially on the sublittoral 

 algæ, 4) that the algæ could neither fix themselves again after the 

 drift across the sea, nor develop new reproductive organs, these 

 being lost presumably on the way. Consequently, even though cases 

 are known of marine algæ having drifted a long way, yet the pro- 

 bability of any effective distribution occurring in this way is ex- 

 tremely small, and so far as known it has never been observed. 

 Further Porsild opposes the possibility that algoid spores may be 

 distributed widely by the oceanic currents, and considers navigation 

 of no importance as a means of distribution. In faet, according to 

 Porsild, the algal flora of the Færoes can only have arisenthrough 

 some postglacial communication with land. 



Simmons entirely agrees wåth Porsild 's view-. He also endea- 

 vours moreover, to criticise my description of the algal commu- 

 nities and my comparison of the Færoese flora with that of the 

 neighbouring lands, and, for this purpose gives a list of the algal 

 forms of the North Atlantic as well as of the Arctic Ocean. I shall 

 nol enter upon further details here, however, but merely mention 

 that his list is not drawn up with sufficient accuracy to enable it 

 o form the basis of a thorough comparison. 



I. 



ON THE EXTERNAL CONDITIONS AFFECTING THE ALGAL 



VEGETATION ON THE FÆROESE COASTS. 



1. Climatic and hydrographic conditions. 

 a. Temperature and Salinity of the Sea. 



The Færoes, lie in the Atlantic Ocean in 61 <^ 23'— 62'' 24' N. 

 Lat. and 6° 14' — 7*^41' W. Long. The chmate is markedly insular, 

 the temperature very uniform, in summer low, but in winter rela- 

 tively high. Rain and fogs are frequent, and the climate on the 

 whole stormy and rough. Consequently the sea is most often in 

 motion, and on exposed coasts there is much surf. 



This very rough climate is mostly due to the faet that the 

 boundary line between the warm Gulf Stream and the cold East 

 Icelandic Polar Current is found at, or at anv rate near bv, the 



