242 FIRST FORMS OF VEGETATION. 
the snow upon the ice, at a distance of many miles 
from the land. It affords a welcome food,—far 
more palatable than the Tripe de roche, the only 
other edible substance which occurs in these in- 
hospitable regions,—consisting as it does of a mo- 
dification of cellulose, without any deleterious mix- 
ture. It affords food and shelter to several species 
of Podurz, and an interesting little spider called 
Desoria Arctica. In the warm springs of India 
the Nostoc frequently occurs, and is successfully 
employed by the natives as an outward applica- 
tion for scrofulous affections, owing to the presence 
in it of minute quantities of an alkaline iodide. 
In China it is a frequent denizen of ponds and 
streams, whence it is carefully gathered and dried, 
to form an ingredient in the famous soup made of 
edible bird’s nests. In the salt lakes of Thibet, 
and the marshes in the woods of New Zealand, it 
attains frequently gigantic proportions, forming 
masses of quaking gelatine, many feet in cir- 
cumference. Country people suppose the Nostoc 
to be the remains of a fallen star, or of a Will- 
of-the-wisp, and hence they call it sty or star-jelly, 
and attach many superstitious ideas toit. Cowley 
in his poem on Reason graphically alludes to this 
strange fancy. It derived its name from Paracelsus, 
who employed it owing to its simple structure in the 
composition of the elixir vite. We find frequent 
