252 FIRST FORMS OF VEGETATION. 
that, in his time, they were in much repute as a 
healing remedy for fractured limbs. They some- 
times abound to such an extent as to be posi- 
tively injurious to health. After floods, for 
instance, when the overflow stands several days, 
they grow and spread with such rapidity, as on 
the subsidence of the water to form a uniform paper- 
like mass, to which the name of meteoric paper 
has been given. Till the stratum becomes per- 
fectly dry, which is a slow process, except on the 
outer surface, the smell is often very disagree- 
able, and the gas generated from it renders the 
meadows extremely unwholesome. Every one 
must have remarked the unpleasant odour ex- 
haled by streamlets when their waters begin to 
fail in a hot summer, and thus expose the masses 
of conferve which they contain. Specimens of 
the so-called meteoric paper have been preserved 
in the library of Bernhedin. One side is smooth, 
and of a brownish-ash colour, the other of a 
greenish red-brown. One of the pieces preserved 
was thirty-four feet long and three feet wide. 
The grey side was the more compact, and much re- 
sembled grey blotting-paper. It received its paler 
hue from the bleaching effect of the sun’s rays. 
The fresh-water alge of foreign countries are 
very similar to our own. Fewer differences exist 
between native and foreign species of this family, 
