THE SARGASSO WEED. 283 



This species of the Sargassum, found in such 

 immense quantities, floating upon the surface of 

 the ocean, is of a fine yellow colour, lighter or 

 deeper in tint, being when very young of a 

 greenish yellow colour ; it is very buoyant, oc- 

 casioned both by its lightness of structure and body 

 of water to support it, as well as by the number 

 of air vesicles with which it is profusely covered ; 

 it has a handsome appearance when seen spread 

 out and swimming on the surface, or when just 

 taken out of the water. On drying, it first re- 

 tains the yellow, or greenish yellow, afterwards 

 becoming of a reddish brown colour, but turning 

 black, if exposed to the atmosphere when dry- 

 ing. The leaves are long, narrow, scattered, 

 serrated at the edges in an irregular manner; 

 the stems are studded with numerous air- 

 vesicles in diff'erent stages of growth, spherical, 

 and attached by a short pedicle to the stem. In 

 many instances a young leaf would be seen 

 emerging from the air-vesicle, and in others 

 many of the leaves would have the air- vesicle 

 (instead of being, as usual, on the stems) at the 

 summit, forming a rounded termination to the 

 leaf ; some of the vesicles would have a longer 

 and broader pedicle than usual, which assumed 

 the character of an embryo leaf just forming, 

 similar to what has been just mentioned as oc- 



