234 ALG^E. CHAP. IV. 



ing on the bark of trees, or on rotten wood, or on 

 stones and rocks, or in damp vaults or cellars, and 

 on wine casks, where it is often so extremely fine 

 and delicate, that the slightest breath or touch will 

 disperse or dissolve it. 



Tremellse. In the Tremella it is a gelatinous and often pel- 

 lucid substance of no regular or definite shape, but 

 chiefly of terrestrial habitat, being found for the 

 most part on decayed stumps and branches of trees, 

 or on stones and gravel walks, or on meadows and 

 pastures after rain, where it is sometimes found re- 

 sembling a large lump of transparent jelly, which 

 people unacquainted with botany are apt to regard as- 

 the congealed remains of what are vulgarly called 

 shooting stars, after having fallen to the ground. 



Ulva, In the Ulv& it is a thread-like and tubular sub- 



stance, or a flat waved and leaf-like membrane, or 

 a sort of spongy and viscid pulp, chiefly aquatic, 

 though partly marine and partly inhabiting pools 

 or lakes of fresh water, and but rarely found on 

 the surface of the earth. 



In the Conferva it is a fibrous and thread-like 

 substance, jointed, forked, or branched, with the 

 threads closely matted together, and extricable 

 only by immersion ; being wholly acquatic, but 

 partly also marine, and partly inhabiting pools, cis- 

 terns, or rivulets of fresh water.* 



* The subject of Fresh-water Confervas has lately been much 

 illustrated by M. Jean Pierre Vauclier, of Geneva. Lit. Jourru 

 TO!, i. 491. 



