ON SEA -WEEDS. 153 



vidual plant belongs, the width of the frond is so 

 different; sometimes it is an inch across its widest 

 part, sometimes not a twelfth part of that width. 

 Then it divides itself into such various shapes; some- 

 times the segments at the edges being round, in others 

 acute or jagged, or forming long slender points; and 

 if this sea-weed grows in a spot where it is exposed 

 to the influence of fresh water, it alters so much that 

 an ordinary observer of marine plants would think it 

 belonged to a different genus. Then its colour is 

 variable. When growing in a shady pool it is irride- 

 scent ; while it has been lying, it is bleached perfectly 

 white, when it may be seen in all the intermediate 

 tints between white and dark purple, often tinged, 

 too, with green. Nor is it even constant in its place 

 of growth ; for on the very shore where in one spring 

 it lies in great profusion, it is not unlikely that in 

 the following year a few specimens only will be 

 found."* 



Perhaps the most notable of all marine plants for 

 purifying the water of the tank is the blood-coloured 

 Fucus, the scientific name of which is Delessaria san- 

 guinea. This Fucus has the good fortune to be a 

 great favourite with the lady collectors. I have seen 

 specimens so cleverly mounted upon card-board, or 

 the pages of an album, that although the fair artist 

 told me she had " collected" them herself, I could 

 not resist slily scraping the edge of the weed with 

 my thumb-nail, to make sure I was not being plea- 

 * Miss Pratt, " Things of the Sea-coast." 



