80 SEA MOSSES. 



vessels in the extremities of the branches, which are, 

 in that case, much swollen, and of a pronounced 

 yellow color. Cut through with a knife, these swollen 

 receptacles will appear to consist of a mass of hard 

 gelatine, and the seed vessels will show themselves as 

 bright yellow spots, all around the circumference. The 

 distinct olive green color of the fresh plant changes 

 to black in drying. 



FUCUS NODOSUS, L. 



Our next most common " Rockweed," is the 

 " knotty " Fucus, so called, from the knots or swell- 

 ings which the interior air vessels make in the frond. 

 This species differs from the last in several impor- 

 tant respects : first, by having a very narrow frond, 

 of the same width throughout, one-quarter of an inch 

 or more; second, by its method of branching, 

 which is not in regular forks, but by putting out side 

 branches of various and irregular lengths, commonly 

 quite long, from the sides of the main stem ; third, by 

 the presence also with the branches of short (three- 

 quarters to one inch long) branchlets, whose wider 

 ends thicken and produce the seed vessels ; and fourth, 

 by the prominent swellings or knots in the stem, and 

 branches which give the species its name. This and 

 the other Fuci are fastened to the rock on which they 



