54 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 orients. 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 



* Drumuioud. 



