THE SHORES OF BRITAIN. 63 



lows in miniature. Beyond its beauty I know 

 not that this little creature has any obvious claim 

 to our consideration, except that, in common with 

 other sea-plants, it gives out oxygen, and thus 

 maintains the element in which it grows in a state 

 fit for the support of animal life. But this is a 

 service vastly important, and explains why the 

 "floor of the ocean" is covered, as it appears to 

 be, with such a profusion of vegetable life. And 

 here so wisely is the balance kept up between the 

 animals which absorb oxygen and the plants which 

 evolve it, that, perhaps, the world could not afford 

 to lose a single species of either without derange- 

 ment of the existing order, which would be fol- 

 lowed by manifest inconvenience. Of course our 

 little Coralline cannot do much to promote this 

 object ; but that it does exert some beneficial in- 

 fluence, we have evidence in an experiment of 

 Dr. Johnston, whose researches on these neglected 

 tribes are so interesting. "Was there a need," he 

 observes, " of adding any additional proof of the 

 vegetability of the Corallines, an experiment in pro- 

 gress before me would seem to supply it. It is 

 now eight weeks ago since I placed in a small 

 glass jar, containing about six ounces of pure sea- 

 water, a tuft of the living Corallina officinalis, to 

 which were attached two or three minute Conferva, 

 and the very young frond of a green Ulva, while 

 numerous Rissoce, several little Mussels, and An- 

 nelides, and a Star-fish, were crawling amid the 

 branches. The jar was placed on a table, and was 

 seldom disturbed, though occasionally looked at; 



