THE DAWN OF LIFE l8l 



shell. Now if the Laurentian graphite represents an 

 exuberance of vegetable growth in those old seas 

 proportionate to the great supplies of carbonic acid 

 in the atmosphere and in the waters, and if the 

 Eozoic ocean was even better supplied with carbon- 

 ate of lime than those Silurian seas whose vast 

 limestones bear testimony to their richness in such 

 material, we can easily imagine that the conditions 

 may have been more favourable to a creature like 

 Eozoon than those of any other period of geological 

 time. 



Growing, as Eozoon may be supposed to have 

 done, on the floor of the ocean, and covering 

 wide patches with more or less irregular masses, 

 it must have thrown up from its whole surface 

 its pseudopods to seize whatever floating par- 

 ticles of food the waters carried over it. There is 

 also reason to believe, from the outline of certain 

 specimens, that it often grew upward in inverted, 

 conical, or club-shaped forms, and that only the 

 broader patches were penetrated by the tubes or 

 oscula already mentioned, admitting the sea-water 

 deeply into the substance of the masses. In this 

 way its growth might be rapid and continuous ; 

 but it does not seem to have possessed the power 



