ULVACE^. 253 



readily determined by the total absence of branches of 

 any description. The Japanese use this weed to thicken 

 soups, much as vermicelli is used in this country. Pro- 

 bably the substance which is occasionally imported from 

 China, under the name of " artificial birdVnest," and 

 which is, as I can testify from personal experience, ap- 

 plied with excellent effect to the same purpose, has a 

 like, or at least a kindred origin. 



, Enteromorpha compressa. The compressed 

 Enteromorpha. 



Frond branched, elongate, tubular or somewhat com- 

 pressed; branches long, simple, gradually tapered at the 

 base, obtuse at the tip. Fructification in the cells of the 

 membrane of which the frond is composed. 



In nearly every latitude this plant abounds, both on 

 the seacoast and in the estuaries of tidal rivers. It 

 grows at all seasons on rocks, shells, and woodwork, and 

 varies very much in size. It frequently covers a vast 

 extent of the surface of perpendicular rocks, and marks 

 the level of high tide. In such situations its fronds are 

 numerous, densely packed, and small, like stunted, very 

 bright green grass. In the shore pools it is more fully 

 developed, and at those points where fresh water flows 

 into the sea, its fronds reach their maximum luxuriance, 

 attain considerable length and breadth, and become in- 

 flated. 



Enteromorpha clathrata. The latticed Entero- 

 morpha. 



Frond much branched, slender, tubular, cylindrical ; 

 branches more or less spreading, sometimes squarrose, be- 



