MR. WARINGTON'S COLOURED MEDIA. 19 



occurred to him that it might be possible to obviate 

 such a drawback, and at length he succeeded, after a 

 number of experiments, in overcoming this inconve- 

 nience, and in retaining them, in all their natural love- 

 liness, efficient for the purposes required ; that is, as 

 consumers of carbonic acid and generators of oxygen. 



The considerations on which these experiments were 

 founded, were based upon the circumstance that nearly 

 the whole of these red or pink-coloured sea-weeds are 

 found either in deep water or under the shade of other 

 Algae ; whilst, from the fact that they are often also 

 known to occur in shallow rock-pools, it seemed fair to 

 assume that the pressure of the superincumbent column 

 of water could not be an important element in the pro- 

 duction of these coloured growths, and therefore that it 

 must depend upon a modification of the light. Hence, 

 Mr. Warington conceived the idea that the effects of 

 the depth of water might be imitated by tinting the 

 light through the interposition of coloured media; and 

 thus all the results observed in the vegetation, and 

 much even of the healthy animal life of deep sea-water, 

 could be, under this arrangement, assimilated ; so that 

 by very simple means and very little trouble, we might 

 be enabled to grow and preserve for any length of time 

 these elegant and beautiful plants in all their varied 

 hues, as well as many of the wondrous forms of animal 

 life associated with them. 



In order to obtain this desideratum, a medium 

 having a blue or green tint, and of such a nature as 

 merely to colour, soften, or diffuse the light without 

 materially diminishing its quantity, has been had re- 

 course to. This maybe accomplished by the employ- 



