24 THE STORY OF LIFE IN THE SEAS. 



the bottom, at the surface, or in the intermediate 

 waters. Great as the influence of direct sun- 

 light must be upon animals, it is even greater upon 

 plants. Nearly all the Sea-weeds are, like the 

 plants of the dry land, dependent upon carbonic 

 acid gas dissolved in the water for one of the 

 most important constituents of their food, but it 

 can only be absorbed by the plant in the presence 

 of sun-light. It is possible, therefore, for Sea- 

 weeds to flourish in the shallow waters of the sea, 

 while they are necessarily absent from the deeper 

 and darker regions to which the rays of the 

 sun cannot penetrate. Everyone knows that in 

 the shallow waters of our own coast there is in 

 many places a dense tangle of Wracks and long, 

 flat ribbon-like Sea-weeds growing on the bottom, 

 and that on and amongst these weeds a rich 

 harvest of animals awaits the eager shore col- 

 lector. It is true that there are vast fields of 

 sand on which the Sea- weeds are few and far 

 between, but we may say that wherever they 

 can obtain a secure foothold in the shallow waters 

 of the British coast there they will grow and 

 multiply in great profusion. We must not, how- 

 ever, jump too hastily to the conclusion that the 

 same is true for all parts of the world. The 

 British coasts are particularly rich in Sea-weeds, 

 in fact a distinguished botanist once said that 

 they probably present us with the greatest 

 number of genera and species of any coast-line 

 of the same extent in the world. In the Tem- 

 perate regions of both the Southern and Northern 

 Hemispheres there is generally a rich Sea-weed 

 flora, but in the warmer regions it is less luxu- 



