80 KJELLMAN, THE ALG^ OF THE AECTIC SEA. 



The conditions of life of the arctic marine algae. 



On the western coast of Sweden the composition of the marine vegetation changes 

 in a remarkable degree at different seasons. Besides a number of species occurring 

 and developing all the year round, in summer as well as in winter, there is to be found 

 a pretty considerable number which are constantly met with during a fixed period, 

 but are wanting during the rest of the year. Again, otlier species are met with, in- 

 deed, during the whole year, but are in course of development only during part of it. 

 Some species, belonging to these two categories, occur or are in course of development 

 during the warmer part of the year, in spring or summer; others during the colder part, 

 in late autumn or winter; some belong to the litoral zone, others on the contrary to 

 the deeper parts of the sea. I hope to return soon to these facts, which I can only 

 allude to here, and to expose them in detail in a separate paper. 



The facts mentioned show that there are amongst the Scandinavian species such 

 as need not, under the external conditions prevailing in the sea on the western coast 

 of Sweden, a whole year for the purpose of completing their development from spore 

 to spore, or, if they are perennial,, to perform those vital functions whose object 

 is the maintenance of the individual and the species. Thus the external conditions 

 are here such as to make the occurrence of annual species possible. As far as my 

 experience goes, acquired by examining the marine vegetation in different parts of the 

 arctic region and at two different occasions, each time almost throughout a whole year, 

 there are not to be found among the sublitoral and elitoral algse of the arctic Flora 

 any species whose whole development is limited to less than one year. But in a more 

 southerly part of the region, in the Siberian Sea, near Behring Strait, accordingly near 

 the Polar Circle, I found one species, Ehodomela lycopodioides, whose development was 

 interrupted during part of the year, namely, during the winter, in order to be resumed 

 again afterwards, that is to say in other words, a perennial species which did not need 

 the whole year to develop the necessary number of vegetative and reproductive organs. 

 The same species occurs also about thirteen degrees farther northward, on the north 

 coast of Spitzbergen. Here its development is extended to the whole year. It bears 

 a profusion of propagative organs at that season when it is in rest on the north-eastern 

 coast of Siberia. I have not had an opportunity of investigating the litoral algaj du- 

 ring the winter. It is possible, indeed, that some of them, for instance, Urospora 

 penicilliformis, Codiolum NordensUdldianum, Enteromorpha compressa, E. minima a. o. 

 live only during that part of the summer when the litoral zone is free from land- 

 ice, and that they are accordingly annual, being able even in those regions to 

 complete their development in a short part of the year. But all the species are 



