THE -WONDERS OF THE SHORE. 147 



Go down at low spring-tide to the nearest 

 ledge of rocks, and with a hammer and chisel 

 chip off a few pieces of stone covered with grow- 

 ing sea-weed. Avoid the common and coarser 

 kinds (fuci) which cover the surface of rocks ; 

 for they give out under water a slime which will 

 foul your tank ; but choose the more delicate 

 species which fringe the edges of every pool at 

 low water mark ; the pink coralline, the dark 

 purple ragged dulse (lihodi/menia), the Carrageen 

 moss {Chondnis), and, above all, the commonest 

 of all, the delicate green Ulva, which you will 

 see growing everywhere in wrinkled fan-shaped 

 sheets, as thin as the finest silver-paper. The 

 smallest bits of stone are sufficient, provided the 

 sea-weeds have hold of them ; for they have no 

 real roots, but adhere by a small disc, deriving 

 no nourishment from the rock, but only from the 

 water. Take care, meanwhile, tliat there be as 

 little as possible on the stone beside the weed 

 itself. Especially scrape off any small sponges, 

 and see that no worms have made their twining 

 tubes of sand among the wccd-stcms ; if they 

 have, drag them out; for they will surely die, 

 and as surely sj)oil all by sulphuretted hydrogen, 

 blackness, and evil smells. 



