60 HISTORY OF BRITISH ZOOPHYTES. 



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 derangement of the ex- 

 isting order which would be followed by manifest incon- 

 venience." 



As corallines, or nullipores, have now been ascertained to 

 belong to the vegetable world, though they are oxygen-yield- 

 ing, we are not entitled at once to conclude that zoophytes are 

 so also. We are not aware that the experiment has been tried 

 with them; but how easy would it be to place a polypidom ad- 

 hering to stone in pure sea-water in a glass where they might 

 live and be treated in the same manner as Liebig did the 

 animalcules, and the result would soon determine the matter. 

 Our men of science are evidently disposed to think that they 

 are water-purifiers, as appears from the following passage from 

 Kirby's Bridgewater Treatise. " What particular function 

 or office has been devolved by the all-wise Creator upon 

 these zoophytes, which are produced so rapidly and in such 

 numbers on the bed of the ocean and rocks, has not been 

 ascertained. As in the case of a vast variety of other ma- 

 rine animals, they probably derive their nourishment from 

 the contents of the water absorbed by their tubes ; they may 



