16 SEAWEEDS 



size of the sun in the early stages of the earth's his- 

 tory an idea first introduced into geological specu- 

 lations by Blandet (Bull. Soc. Geol. de France, ser. 2 

 t. 25, p. 777, 1867-68), who likewise discussed the 

 relations of Arctic and Antarctic faunas together 

 with the greater amount of aqueous vapour in the 

 atmosphere and the greater mass of the atmosphere." 

 (Murray, in Summary of Results, " Challenger " Reports, 

 1895.) 



Another interesting point in the distribution of 

 seaweeds bearing on this subject is that those 

 having an incrustation of carbonate of lime occur 

 much more plentifully in the warmer oceans a fact 

 equally true of the marine animals, though the pro- 

 cess of deposition is different. This very slight 

 development of carbonate of lime structures in the 

 cold waters of the polar regions is instructive when 

 compared with the massive coral reefs constructed 

 in the polar regions in Palaeozoic and later geological 

 times. 



It is a commonplace of biological knowledge that 

 the nutrition of the animal kingdom is dependent 

 upon the action of green vegetation in performing 

 the primary office of converting the inorganic into 

 the organic, and thus producing fitting substances 

 for food. A casual observation of the great mass of 

 terrestrial vegetation, and a comparison of it bulk for 

 bulk with the animal life of the land, enables us to 

 recognise the adequacy of the one as a balance to the 

 other. On turning to the conditions that prevail in 

 the ocean, it is at once apparent that a mere fringe of 

 coast vegetation, extending to no great depth, can- 



