VIII. SOME NOTES ON THE BIOLOGY OF THE 

 ALG^ ALONG THE COAST OF ICELAND. 



At present very little is known with regard to the biology of 

 . the marine alga? along the coast of Iceland. What is known, 

 on the whole, regarding this point is for the most part mentioned 

 in the "Marine Algse of Iceland" (31) under each species. Some ob- 

 servations which have been made subsequently will be mentioned 

 in the following pages. Of these, I regard those which have been 

 made during winter as the most important, although they are very 

 incomplete owing to the fact that during winter I have only rarely 

 been able to make investigations, and then have had access to the 

 littoral zone only; thus, with the exception of a few species, the 

 winter-habit of the sublittoral species is not known. Consequently 

 I can, by no means, treat of the biological conditions exhaustively, 

 but must content myself with giving a few incomplete contributions. 



On the whole, the behaviour of the species is best known in 

 spring and summer, less well in autumn, and least well during 

 winter. From most of the coastal districts there are observations 

 to hand either only those of a single season of the year, or at most 

 of two or three seasons. From Reykjavik we have observations of 

 all four seasons, but those of the winter are sparse, and only a few 

 species have been observed throughout the year. 



The observations to hand are so few and insufficient that a 

 comparison of the biological conditions in the five coastal districts 

 in question cannot be made; here, therefore, Iceland is treated for 

 the most part as an entirety. 



1. Duration of Life. 



The life-period of the algal species is of very varying length; 

 in this connection the algse may be divided into two groups: annual 

 algae and perennial algse. 



