MAN’S FOOD

Greymouth Evening Star, 28 November 1927, Page 8

MAN’S FOOD

DREAMS OF THE FUTURE.

The age-old mystery of how the green colouring matter of the leaf changes the inert gas carbon dioxide into valuable foodstuffs such as starch and sugar (known to chemists as car-bo-hydrates) is rapidly approaching solution, says the “Morning Post.” Pro, fessor E. C. Baly, F.R.S. and his fel-low-workers in the bio-chemical school at Liverpool have just published the second series of their experimental results in the Proceedings of the Royal Society. , For years botanists in the Royal Society, the Linnaean, and elsewhere, have attempted to -trace in detail the mechanism by which the plant stores up sugar and starch and sets free oxygen into the air. It has long been known that the transformation is effected by means of the green colouring matter of the plant acting under the influence of light. There have, however, been many problems baffling to the investigator. Carbon dioxide is a colourless and inert or idle gas. When it comes into contact with the leaf nothing happens, but when it comes into contact with the leaf in sunlight a change occurs, and the result of the process is the production of such highly complicated substances as sugar and starch. The green colouring matter itself is in abeyance in the absence of light, as everyone knows who has turned over a stone and seen the pale whitish stems where the plants have been condemned to grow in darkness. They suffer from the pallor of the slum child—no unfair analogy, as there is a certain chemical similarity between the red colouring matter of the blood and the green colouring matter of the plant. To track the carbonic acid gas through its protean changes has been no easy matter. The problem was formerly regarded as simple, but experiment showed that it was very complex and the beautiful easy formulae which were held to explain the change have long been abandoned. More recently a second aspect of the problem came to the front with the advent of the bio-chemical school. Year by year the great gulf separating the living from the non-living has narrowed. Wohler was one of the pioneers, showing that a substance believed to require animal agency ioy its production could be produced by the chemist in the laboratory. Wohler’s work was like the thread of a spiderthat carried its maker across the gulf. Pasteur emphasised rather the difference between the living and the non-living, but since his time men of science have tried repeatedly to throw a solid plank across the chasm and to prove that tlie transition between the non-living can be achieved. For many years the Liverpool school has worked at the problem. The writer remembers the speculations of Benjamin Moore at one of the British Association meetings, and how 1 he adduced experiments which hp thought indicated how the living could be synthesised —“created” if one likes—from the non-living.

Professor Baly and his colleagues have attempted something at once more and less ambitious. They have not tried to derive living from nonliving matter, but they have taken Nature’s greatest miracle, in which Nature had bridged the gulf between plant and animal, and have attempted to follow in her footsteps and determine how far the processes she has been carrying out long before the carboniferous ages until to-day can be imitated by inanimate substances. Three papers are published simultaneously in the current number of the Proceedings of the Royal Society. They were received on 27th July, when the society was in vacation, but their importance was considered such, that they were passed for publication, and may or may not come up for discussion by the society when it resumes its weeklj’ meetings.

The first two papers are technical, but the third draws attention to the analogies that have been observed between the behaviour of the green leaf acted on by sunlight and that of chemicals, such as the coloured carbonates of nickel and cobait, subjected to the same influence. The general broad conclusions of the authors is that a marked similarity exists between the synthesis occurring in the living plant and that which can arise through non-living substances acted on in the laboratory. The main similarities of behaviour that have been established are as follows: — '

(1) Ordinary formaldehyde does not take part in the reaction in either case. (2) The laboratory process has been realised by the action of light on carbonic acid condensed on to a nonliving surface, and there seems no doubt that limiting surface exists in the leaf, and is necessary for the synthesis by light to take place. (3) A visibly coloured surface and visible light take place in each of the two processes.

(4) A marked fatigue is observed when the living leaf is exposed to too long and intense illumination, and very intense illumination destroys the green colouring matter. In the laboratory a similar fatigue effect, due to poisoning of the surface by oxygen is observed. Intense and prolonged illumination destroys the carbohydrate formed, though there is nothing anal-

ogous to the green colouring matter of the plant. (5) In both processes there is a slow recovery reaction, and it appears that in both the light synthesis must not proceed at a more rapid rate than that recovery reaction. (6) The total yield of organic products so synthesised in the laboratory per units of time and surface is not seriously at variance with that produced in the leaves of four plant BpGCiGS. (7) As production under the influence of light must not exceed the rate of recovery, it follows that there must be present in the living leaf some internal mechanism which controls the rate of synthesis by means of light so that it does not exceed that of the slow recovery reaction. So far the authors have only rung up the curtain on their discovery, but they speak also, guardedly, of the synthesis of nitrogen compounds which may or may not have their importance in another direction as having a close relation to the possible synthesis of protoplasm. . What is the significance of this work? At present it shows nothing more than that there is a close analogy between Nature’s methods and the methods of the laboratory in that in many instances the same or similar results are obtained as the result of the same stimulus. Looking to the future, one may hope to see that analogy more clearly understands . derstood and more precisely defined. If the analogy between the plant and the chemical can be made absolute so far as the change from carbon dioxide to carbohydrate is concerned, the world’s food supply should be ensured so far as the essential carbohydrates are concerned, and an unlimited supply should be available so far as this class of foodstuffs is concerned. The idea may seem fantastic, but Franklin, after a celebration of his electrical work, wrote despondently, saying how sad it was that electricity seemed likely never to be of use to anybody. Oersted, too, did not realise the importance of the fact that a magnet held over a wire through which an electric current was passing turned at right angles to it, and did not publish the fact for a year. But that was the basis of electro-magnetism. One the other hand, Crookes, when president of the British Association, drew attention to the horrors of a nitrate famine. The breath was scarcely out of his body when the problem had been solved. To abide by the facts botanists can rejoice at a great advance in the physiology of botany, and visionaries need not be blamed if they see a long vista of possibilities stretching out before them.