64 THE OCEAN. 
coming in contact with the air, and contracts with 
a force remarkable when we consider its extreme 
thinness. If the paper be thin, its four corners will 
in a moment be brought almost in contact with each 
other.” The best method of obviating this incon- 
venience is said to be, when we suppose it is almost 
dry, to have a flat book held open, and the pressure 
being taken off, to remove the specimen along with 
the drying-paper covering it, as quickly as possible 
into the book, which must be instantly shut, and not 
opened till the next day, or till we know that it is 
thoroughly dry.* 
There is a substance which has been lately intro- 
duced as an article of commerce, intended as a sub- 
stitute for Iceland moss, and sold by the London 
druggists by the name of Carrageen moss; notwith- 
standing its name, however, it is a true Alga, Chon- 
drus crispus. It is an exceedingly variable species, 
but its most usual form is that of a flat leaf, spreading 
somewhat triangularly, or rather so as to give to its 
outline the figure of one-fourth of a circle: the edge 
is branched into numerous flat segments overlapping 
one another. When viewed under water, in a grow- 
ing state, it gives out beautiful prismatic hues. Con- 
taining a large quantity of gelatine, it has been suc- 
cessfully applied, instead of isinglass, in the making 
of blanc-mange and jellies. A fucus, probably allied 
to this, found at the Cape of Good Hope, is boiled 
into a jelly, and, being mixed with sugar and the juice 
of lemons or oranges, makes a very agreeable dish. 
I shall notice a few other Alga, remarkable either 
* Drummond, 
