Factors Influencing Plant-Life on Sandy Sea-shores. 47 
On many shores, which are protected by outlying banks or 
islands, the action of waves is considerably lessened, or, in some 
cases is absent. Such shores in different positions can be seen 
in abundance in the Archipelagos of the Baltic, while most other 
coasts observed by the writer in this connection have been 
unprotected from the open sea. 
Except in their landward urging of sediments the waves are 
also incidental agents of breaking off and transporting fragments of 
plants both on the submerged and front beach. 
Currents in the sea are, however, of still more marked significance 
for transportation of spores, seeds, fruits and shoots of plants, and 
must be considered as an important factor in the distribution of 
coastal floras. 
To the plants living in the water, currents are of the greatest 
consequence because they continuously change the surrounding 
medium, thus bringing within reach of the plant the necessary 
foodstuffs. While some plants are able to exist in the heaviest 
surf, e.g., many algae and Phyllospadix, others prefer water with a 
steady current, and others again grow only in quiet water. 
Salinity of sea water is another factor which exerts a great 
influence on those plants which come into direct contact with the 
water, and indirectly also on the shore vegetation by affecting the 
salinity of the atmospheric moisture. Most of the salts contained 
in sea water do not constitute any food for the plants, but are 
important by their influence on the turgor. It is, however, the 
variations and changes in the salinity on a given coast, which 
determine the aspect of the vegetation, rather than the larger or 
smaller amount of salts contained in the water. This is noticeable 
on many coasts where the salinity is stable, and not subjected to 
occasional diminutions by the influx of freshwaterfrom the overflow 
of rivers. The general character of the sea-shore vegetation on the 
open coasts along the Baltic, with a salinity less than 1%, is similar 
to that of the North Sea shores with a salt-content in the water of 
1-5% and of the West Coast of France with a salinity of 2-5% in the 
Atlantic Ocean. The sea coast of California presents a vegetation 
on the sands which does not materially differ from that of the 
Baltic, and even the sub-tropical coasts of Queensland, where the 
salinity is 2-9% show a closer relationship to the general marine 
coast vegetation of Europe, than do the sea-shore plants in the 
outer Finnish Archipelago to those in the innermost part of the 
same Archipelago, only about 200 km. distant, but with a salinity 
