Page:The Scientific Monthly vol. 3.djvu/23

 THE EVOLUTION OF LIFE 17

In Table I all the *^life elements^' which enter more or less freely into organic compounds are indicated by italics, showing that life has taken np and made use of practically all the chemical elements of fre- quent occurrence with the exception of aluminum, barium and stron- tium, which are extremely rare in life compounds, and of titanium, which thus far has not been f otmd in any. But even these elements appear in artificial organic compounds, showing combining capacity without biological "inclination*' thereto. In the life compounds, as in the lithosphere and hydrosphere, it is noteworthy that the elements of least atomic weight predominate over the heavier elements,

PRIMORDIAL ENVIRONMENT — THE LIFELESS WATER

According to the theory of Laplace the waters originated in the primordial atmosphere; according to the planetesimal theory of Cham- berlin*' and Moulton^' the greater volume has been gradually added from the interior of the earth through the vaporous discharges of hot springs. As Suess observes,

The body of the earth has given forth its ocean.

From the beginning of Archeozoic time, namely, for eighty million years, we have little biologic or geologic evidence as to the stability of the earth. From the beginning of the Paleozoic, namely, for a period of thirty million years, the earth has been in a condition of such stability that the oceanic tides and tidal currents were similar to those of the present day; for the early strata are full of such evidences as ripple marks, beach footprints, and other proofs of regularly recurrent tides."

As in the case of the earth, the chemistry of the seas is a matter of inference, i, e., of subtraction. The relatively simple chemical con- tent of the primordial seas must be inferred by deducting the mineral and organic products which have been sweeping into the ocean from the earth during the last eighty to ninety million years ; and also by deduct- ing those that have been precipitated as a result of chemical reactions, calcium chloride reacting with sodium phosphate, for example, to yield precipitated calcium phosphate and dissolved sodium chloride.*" The present waters of the ocean are rich in salts which have been derived by solution from the rocks of the continents.

Thus we reach our first conclusion, namely : it is probable that Kf e originated on the continents, either in the moist crevices of rocks or soils, in the fresh waters of continental pools, or in the slightly saline waters of the bordering primordial seas.

As long ago as 1715 Edmund Halley suggested that the amount of

as Ghamberlin, Thomas Chrowder, 1916. S8 Monlton, P. B., 1912, p. 244. w Becker, George F., 1910, p. 18. M W. J. Gies.

TOii. in. — 2,

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