FRESH-WATER ALG. 223 
and mosses, exposed to occasional or frequent 
inundations of water, seems to prove that the ice- 
plains of the Arctic regions, and the snow-crowned 
sides and summits of the European mountains, 
are not its natural situations. When, however, its 
germs have once been deposited in these barren 
and cheerless localities, the simplicity of its or- 
ganization, and the consequent strong persistency 
of the vital principle in it, enable it effectually to 
resist the cold ; and with that extraordinary power 
of rapid development which characterizes in a 
greater or less degree all the members of the 
family to which it belongs, it forms in a few years, 
when nourished by the moisture produced by the 
melting of the icy snow during summer, vast and 
dense masses, sometimes twelve feet in depth, and 
extending many miles in length, which afford by 
their strange contrast to the painful uniformity of 
the pure and dazzling whiteness all around, a 
sight more surprising to the Arctic or the Alpine 
traveller than would be the realization of all the 
fabled wonders of the Arabian tales. 
Another supposed species of Protococcus was 
discovered by Baron Wrangel in the province of 
Nerike or Nericia in Sweden, not far from the 
town of Orebo, and named by him Lepraria Ker- 
mesina, The same plant was afterwards found by 
various continental botanists among the fissures 
