664 EVENING DISCOURSE. 



that the organised structure of these cells is a chemo-dynamic structure which requires 

 oxygen, and therefore oxidation, to preserve it. The organisation, the molecular 

 structure, is always tending to run down, to approach biochemical chaos and dis- 

 organisation. It requires constant oxidation to preserve the peculiar organisation 

 or organised molecular structure of a living cell. The life machine is therefore 

 totally unlike our ordinary mechanical machines. Its structure and organisation are 

 not static. They are in reality dynamic equilibria, which depend on oxidation for 

 their very existence. The living cell is like a battery which is constantly running down, 

 and which requires constant oxidation to keep it charged. It is perhaps a little 

 premature at the present moment to say how far these results will prove to be general. 

 Personally, I believe that they are of great importance and generality, and that 

 for the first time in the history of science we begin, perhaps as j'et a little dimly, to 

 imderstand the difference between life and death, and therefore the very meaning of 

 life itself. Life is a dynamic molecular organisation kept going and preserved by 

 oxygen and oxidation. Death is the natural irreversible breakdown of this structure, 

 always present and only warded off by the structure-preserving action of oxidation. 



The last great problem which I shall venture to consider in this brief sketch concerns 

 the origin of life. It might indeed be argued with much justice that such considera- 

 tions are so far beyond the present stage of science that they are entirelj' without 

 value. That, I think,- is a bad argument and a worse philosophy. But, in any case, 

 a dealer in mysteries is entitled to carry on his dealings as far and as best he may. 



There appear to be two schools of thought in speculations of this character. The 

 late Prof. Arrhenius supported the theory or doctrine of Panspermia, according to 

 which life is as old and as fundamental as inanimate matter. Its germs or spores 

 are supposed on this view to be scattered through the universe and to have reached 

 our planet quite accidentally. You will remember that Lord Kelvin suggested they 

 were carried here on meteorites. But against this idea the objection has been urged 

 that meteorites in passing through our atmosphere get exceedingly hot through friction 

 with the air. Arrhenius brought forward the very ingenious idea that the motion 

 in and distribution through space of these germs or spores were caused by the pressure 

 of light, which in the case of very minute bodies can overcome the attraction of 

 gravitation, as is often seen in the tails of comets. Many objections have been brought 

 against this theory of Panspermia. It has been argued that either the cold of inter- 

 stellar space or the ultra-violet light which pervades it would be sufficient to kill 

 such living germ or spores. Certainly ultra-violet light is a very poweiful germicide, 

 though many spores can withstand very low temperatures for long periods of time. 

 Perhaps the chief objection to this doctrine of Panspermia is that it is a hopeless one. 

 Not only does it close the door to thought and research, but it introduces a permanent 

 dualism into science and so prejudges an important philosophical issue. 



If the living has arisen on this planet from what we regard as the non-living, then 

 various extremely interesting points arise. 1 1 is already pretty certain that it originated, 

 if at all, in the primeval ocean, since the inorganic salts present in the circulating 

 fluids of animals correspond in nature and relative amounts to what we have good 

 reason to believe was the composition of the ocean some hundred milhon years ago. 

 The image of Aphrodite rising from the sea is therefore not without scientific justifica- 

 tion. We have seen that life requires for its existence a certain amount of free energy 

 or non -equilibrium in the euvironment. In the early atmosphere there was plenty 

 of carbon dioxide, and probably also some oxj'gen, though nothing like so much as 

 at present. Volcanic action would pro\'ide plenty of oxidisable substances, such, for 

 example, as ammonia or sulphuretted hydrogen. As we have seen previously, certain 

 bacteria could therefore, in all probability, have lived and assimilated carbon dioxide, 

 producing organic substances such as sugar and proteins. This argument, though 

 very interesting from the point of view of Panspermia, has a serious flaw in it from 

 the present point of view, since the bodies of these bacteria would necessarily contain 

 the complicated organic proteins of the protoplasm. When the earth cooled down to 

 a temperature compatible with life, it is probable that the ocean contained little, if 

 an}', of such organic substances or their simpler organic components. There was 

 likewise no chlorophyll present to achieve the photo-chemical assimilation of carbon 

 dioxide. Hence the necessity of considering how organic substances could have 

 arisen by degrees in a primeval ocean originally containing onl}' inorganic constituents. 

 The late Prof. Benjamin Moore took up this question and endeavoured to prove that 

 colloidal iron oxide, in the presence of light, moisture and carbon dioxide, could 

 produce formaldehyde, a substance from which sugar can be derived. This work o 



