THE BREATH OF LIFE

Otago Witness, Issue 3830, 9 August 1927, Page 76

THE BREATH OF LIFE

By

Professor J. Arthur Thomson.

For untold ages the earth was void of life. The crust was too hot, and no kind of living creature that we know anything about can exist where there is not water in a liquid state. "It must be remembered that living matter always has at least 70 per cent, of water in its composition. Gradually, however, the crust of the earth cooled, water vapour condensed to form lakes and seas, and the sunshine broke through the thick canopy of cloud. The earth became fit to be a home of life.

How living creatures began to be upon the earth, no one knows. It may be quite true to say that a. living creature is “ a handful of dust which God enchants,” but this is a religious wav of interpreting what happened, it is not a scientific description. The scientific description is still wanting, but the favourite suggestion in scientific circles is that living creatures of a very simple sort may have emerged in some secret, spontaneous way from nonliving materials. It must be admitted that there is not any bint of this happening nowadays, but this does not warrant us in saying that it may not have happened long, long ago. When living creatures make an unexpected appearance to-day, like maggots in the dead bird, like threadworms in a. saucer of decaying paste, it can always be shown that they pot in from outside in some way or other. The mother blowfly laid its eggs in the dead bird ; it may be that a gust of air carried the developing embryos of the threadworms on to the saucer of decaying paste. In every case that has been carefully studied there >s a verification of the conclusion omne vivum e vivo, all life from life. But more precisely than that, every living creature arises from another living creature of the same kind. We have confessed that no one can tell us as yet how living creatures began to be upon the earth, or in the waters under the earth. In the scientific sense of the word knowing, we do not know how the breath of life began. Yet, as it is very unlikely that germs of life came to the earth from elsewhere, borne in the crevices of a meteorite or wafted in the cosmic dust, we are brought more and more to consider the possibility that the first organisms may have arisen from non-living matter —from specks of nitrogenous carbonaceous jelly naturally built up in some quiet pool in the light of the sun. The experiments of Baly and others seem to show that light shining on water with carbonic acid gas in it mav bring about their union, the result being a very simple carbon compound called formaldehyde, with the formula CH-O. From that starting point it seems possible to build up sugar, and we know that this is always being formed by green leaves in the sunshine. The chemist has learned to mimic what takes place in the living leaf. When there is a thunderstorm the electric discharges mav bring about in the damp air a union of nitrogen with hydrogen and oxygen, and there mav be. a production of nitrite of ammonia, and the rain may bring this down to the soil and to the pools. Let us suppose that the rain brought down ammonium nitrite into a sunlit pool where carbon-dioxide and water were uniting to make formaldehyde and other simple carbon compounds, these might capture the ammoniate and form aminoacids, which ha ve been called the “ basic substances” of life. For aniino-acids in combination form proteins, like white of egg ami the casein of milk—proteins which are the main constituents of all living matter. Our point is that in the pool there might be in favourable circumstances long ago a beginning of living creatures of a very simple kind. No one really knows, but there is nothing preI posterous in the idea that living creatures emerged by a continuation of natural processes in a previously life-less, but not mind-less, world. As we cannot juggle “ mind ” out of “ matter,” we must suppose that some form of mind was there all the time. “In the beginning was Mind.”

The first living creatures probably began in the sea, though it is possible that they began in fresh water. If we consider the humbler animals that are living to-day—the simplest single-celled animals, the many-celled sponges, the stinging animals like sea-anemones and jelly-fishes, the multitude of worms, and so on, we find that the. great majority are marine, a small minority' occur in fresh water, and a few simple singlecelled animals are found in the damp soil —forerunners of the earthworms who followed their example long afterwards. If we consider, for instance, the class of sponges, including many hundreds of different kinds, we find that all live in the sea except one family' of freshwater sponges or spongillids. Similarly among the stinging animals (coelentera) there are about half a dozen freshwater

polyps and freshwater swimming bells or

medusoids, but all the others arc marine —thousands of different kinds. Here, then, is a strong argument that the original home of animals was in the sea. A living ci'cature cannot make energy' any' more than an engine can. Both are merely transformers of matter and energy. But the living creature has this unique secret, that it is. for a longer or shorter time a genuinely going concern. It requires food just as the engine requires fuel, but it has processes of upbuilding which eounter-bala.nce for a time the processes of down-breaking. It

can wind up its own elock. For a time it can balance its accounts, in a way that no engine can. The first living creatures were probably minute specks that floated in the sea, neither quite plants nor quite animals, but protista. They were able to utilise the energy of the sunlight to build up carbon-dioxide and water into sugars and other carboncompounds, which formed the fuel of the living fire. The breaking down or combustion of the carbon-compounds was the source of the energy which was expended in moving and growing. We start, then, with a sunlit sea teeming with invisible protista, from which in the course of time there evolved both plants and animals.— John o’ London’s Weekly.