

FERTILITY OF THE SEA. 241 



tion to the extent of its surface, as the land rises 

 above it ; and it is also probable that the fertility of the 

 sea diminishes as the depth increases, just as that 

 of the land does with increase of height. But it is 

 probable, nay, it is certain, that the fertility of the 

 sea cannot diminish so rapidly as that of the land ; 

 because, as we descend there are pressure and con- 

 densation, which are sources of sensible heat, while, 

 as we ascend, there are elasticity and expansion, 

 which are sources of sensible cold. Thus it is nei- 

 ther improbable nor unphilosophical to suppose, that 

 though the inhabitants of the sea vary at different 

 depths, just as those of the land do at different 

 heights, yet that the sea may be well replenished 

 with its peculiar plants and animals at depths mea- 

 suring more than the height of the highest mountain. 

 Consequently, if we carry our imagination backward 

 to the time when the uniform solid spheroid was 

 covered with the two miles of water, we are upon 

 legitimate ground when we say that the surface of 

 that spheroid under the water may have been abun- 

 dantly stocked with plants and animals, and the 

 water itself as abundantly as any part of the ocean 

 is at present. 



We cannot know what was the condition of the 

 water at that early stage of our globe's history 

 whether it was fresh, or impregnated with saline 

 substances as at the present day. Many of the 

 plants, the remains of which are found in the strata, 

 have more the character of fresh-water aquatics 

 than of plants now found in the salt sea. The fishes 

 also have, many of them, the characters of fresh- 

 water fishes ; and as for many of the shells, though 

 we know but little of their inhabitants, perhaps they 

 are as much adapted for fresh water as for salt. 

 When we take all those circumstances into consid- 

 eration, we may perhaps be warranted in saying that 

 the sea which, in those primal days, rolled over the 

 whole globe, was water in a much more simple 



A 



