12 
THE OCEAN WORLD. 
forms of infusoria represented, and among them twenty-two species new 
to him. Generally speaking, the composition of the infusoria of the 
Atlantic are calcareous; those of the Pacific, siliceous. These ani- 
malcules draw from the sea the mineral matter with which it is 
charged — that is, the lime or silica which form their shell. These 
shells accumulate after the death of the animal, and form the bottom 
of the ocean. The animals construct their habitations near the surface ; 
when they die, they fall into the depths of the ocean, where they 
accumulate in myriads, forming mountains and plains in mid ocean. 
In this manner, wo may remark, en passant, many of the existing con- 
tinents had their birth in geological times. The horizontal beds of 
marine deposits, which are called sedimentary roelcs, and especially 
the cretaceous rocks and calcareous beds of the Jurassic and Tertiary 
periods, all result from such remains.* 
The sea level is, in general, the same everywhere. It represents 
the spherical form of our planet, and is the basis for calculating all 
terrestrial heights ; but many gulfs and inlands open on the east are 
supposed to be exceptions to this rule: the accumulation of waters, 
pressed into these receptacles by the general movement of the sea 
from east to west, it is alleged, may pile up the waters, in some 
cases, to a greater height than the general level. 
It had long been admitted, on the faith of inexact observation, that 
the level of the Eed Sea was higher than that of the Mediterranean. 
It has also been said that the level of the Pacific Ocean at Panama is 
higher by about forty inches than the mean level of the Atlantic at 
Chagres, and that, at the moment of high water, this difference was 
increased to about thirteen feet, while at low it is over six feet in the 
opposite direction. This has been proved, so far as the evidence goes, 
to be error in what concerns the difference in level of the Eed Sea and 
Mediterranean, and the opening of the Suez Canal, which is near at 
hand, will probably furnish still more convincing proofs. It is probable 
that errors of measurement have also occurred, so far as the Pacific 
and Atlantic are concerned. 
It has been calculated that all the waters of the several seas 
gathered together would form a sphere of fifty or sixty leagues in 
diameter, and, supposing the surface of the globe perfectly level, that 
* « World before the Delude.’' Second edition. 
