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Page:Popular Science Monthly Volume 4.djvu/741

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EVOLUTION AND THE ORIGIN OF LIFE.

case of living matter. There are no facts easily discoverable upon which such an assumption can be legitimately based.

The probabilities would seem altogether in favor of the continuance of a natural process like Archebiosis after it had been once initiated, more especially when this natural process is so closely allied to another which manifests itself with the utmost readiness on all parts of the earth's surface. So that, unless very cogent reasons could be adduced against the occurrence of Archebiosis at the present day, looked at from an a priori point of view, there seems scarcely room for doubt upon the subject. The properties and chemical tendencies of material bodies seem to be quite constant through both time and space. Speaking upon this subject in a recent discourse on "Molecules," Prof. Clarke Maxwell says:[1] "We can procure specimens of oxygen from very different sources, from the air, from water, from rocks of every geological epoch. The history of these specimens has been very different, and, if, during thousands of years, difference of circumstances could produce difference of properties, these specimens of oxygen would show it. . . . In like manner, we may procure hydrogen from water, from coal, or, as Graham did, from meteoric iron. Take two litres of any specimen of hydrogen, it will combine with exactly one litre of any specimen of oxygen, and will form exactly two litres of the vapor of water.... Now, if, during the whole previous history of either specimen, whether imprisoned in the rocks, flowing in the sea, or careering through unknown regions with the meteorites, any modification of the molecules had taken place, these relations would no longer be preserved.... But we have another and an entirely different method of comparing the properties of molecules. The molecule, though indestructible, is not a hard, rigid body, but is capable of internal movements, and, when these are excited, it emits rays, the wave-length of which is a measure of the time of vibration of the molecule.... By means of the spectroscope the wave-lengths of different kinds of light may be compared to within one ten-thousandth part. In this way it has been ascertained, not only that molecules taken from every specimen of hydrogen in our laboratories have the same set of periods of vibration, but that light having the same set of periods of vibration is emitted from the sun and from the fixed stars.... We are thus assured that molecules of the same nature as those of our hydrogen exist in those distant regions, or at least did exist when the light by which we see them was emitted." With evidence such as this before us, which could be multiplied to an enormous extent, we should hesitate before needlessly postulating any infringement of the uniformity of natural phenomena.

What, then, are the reasons assigned for the non-occurrence, at the present day, of the process of Archebiosis? All that Mr. Spencer says upon the subject is, that such a process seems to him more likely

  1. Nature, September 25, 1873, p. 440.