130 SEA-WEEDS. 



purple are most perfect in hue; and Humboldt 

 speaks of a beautiful marine plant which he found 

 in the sea, near the Canary Isles, the Vine-leaved 

 Fucus, which vegetates at the depth of one hun- 

 dred and ninety-two feet, yet has leaves as green 

 as those of the grass of the spring oak tree. On 

 many of our shores the loveliest sea-weeds are 

 never gathered, though everywhere some of the 

 commonest kinds, as the Hair Flag, lie strewed 

 about the sand or beach. And where there are 

 rocky pools, we may gaze down upon some which 

 redden in the shady nook formed by some little 

 shelving eminence sufficient to protect them from 

 the sun's brightest rays. 



The division of the sea-weeds into the olive, 

 red, and green series, is not an arbitrary, but a 

 natural one, for, in a great measure, with similarity 

 of colour is connected a similar structure. It is 

 not, however, so invariable as to be a perfect dis- 

 tinction. Among the red sea-weeds we find every 

 shade of purple tint, and of a few of the darker 

 kinds we almost hesitate as to whether we should 

 pronounce them to be red or olive-green; while 

 exposure to air and light, in some cases, turns a 

 red sea-weed into a dull yellow or a dirty white 

 hue, or renders its crimson of a bright scarlet; 

 and drying in the sun blackens almost all the 

 olive-green species. Yet in practically studying 

 sea-weeds, this presents little difficulty, for very 

 generally we find the olive-green plants tough and 

 leathery ; the red usually frail and delicate, while 

 the grass-green are always of simplest structure, 

 and of tint little liable to change. In this almost 

 constancy of colour the Algce differ greatly from 

 the plants of our upper earth, among which colou 



