EVOLUTION AND THE ORIGIN OF LIFE. 721 



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 continu- 

 ance of a natural process like Archebiosis after it had been once initi- 

 ated, 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 " Mole- 

 cules," Prof. Clarke Maxwell says : J " 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 cir- 

 cumstances could produce difference of properties, these specimens 

 of oxygen would show it. . . . In like manner, we may procure hy- 

 drogen from water, from coal, or, as Graham did, from meteoric iron. 

 Take two litres of any specimen of hydrogen, it will combine with ex- 

 actly 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-thou- 

 sandth part. In this way it has been ascertained, not only that mole- 

 cules 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 ex- 

 ist when the light by which we see them was emitted." With evi- 

 dence such as this before us, which could be multiplied to an enormous 

 extent, we should hesitate before needlessly postulating any infringe- 

 ment 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. 

 VOL. iv. — 46 



