52 THE CHEMISTRY OF CREATION. 



hues, both of shell and animal; but whilst the 

 animals of such species as inhabit the littoral 

 (or sea-shore) zone are gaily chequered with 

 many vivid hues, those of the greater depth, 

 though their shells are almost as highly coloured 

 as the coverings of their allies nearer the sur- 

 face, have their animals, for the most part, of a 

 uniform yellow, or reddish hue, or else entirely 

 white. The chief cause of this increase of in- 

 tensity of colour as we ascend, is doubtless 

 the increased amount of light above a certain 

 depth." The sea-weeds and fish which have 

 their abode near the surface of the water are 

 far more beautiful than those which are found 

 deeper down ; and where the finny tribe live at 

 the bottom, or at depths where a mere glimmer of 

 light is all that distinguishes day from night, they 

 become nearly colourless. On a future page, it 

 will become necessary for us to enter more fully 

 into the chemical influence of light upon the 

 vegetable world, where it will be found that the 

 wood and green parts of plants are principally 

 formed by its agency. 



Not less important is the principle of Heat 

 in the phenomena of nature. It is this which 

 assists to call into activity the germ of life 

 lying dormant in the seed; this bids the in- 

 sect's egg awake and live ; this breaks up the 

 hard and stony surface of the ice-bound field, 



