LIFE AND ITS MAINTENANCE.*
DrtsprrE its colourless title, this is one of the most interesting books of the year. The most obstinately unscientific person learned during the war to have some respect for the scientific expert. The issue of ration-cards brought the questions of diet—calories, vitamins, and so forth—from the academic to the practical sphere. Agricultural problems became of vital concern to the townsman, who suddenly realized that the production of new varieties of wheat, for instance, might mean more to him than politics or sport. The physiological study of fatigue assumed real importance in the eyes of most of us who were partly or wholly engaged in war work. And when the numbers of wounded began to run into millions, the progress of new methods of anaerobic treatment for wounds was watched with no less anxiety and hope by wives and parents than by the bacteriologists and surgeons. We are sure that the public, having grasped the significance of biological research during the war, will not cease to take an interest in the subject if biologists continue, as in this book, to indicate some of the results of their inquiries in a simple form. The volume is made up of lectures delivered at University College, London, in the early part of last year. Professor Bayliss leads off with a general account of " The Problem of Food," followed by Professor Hopkins on " War Bread," by Miss Margaret Hume on " Vitamins," and Professor Cushny on the much-debated question of " Bread versus Beer." Dr. E. J. Russell and others deal with various important farming problems. Dr. McLean's, account of the " Reading bacillus " which cleans wounds is a veritable fairy-tale of science, and Dr. H. M. Vernon's practical discussion of " Industrial Efficiency and Fatigue " is a moat convincing argument in favour of a shorter—but not too short— working day, as well as a warning against restriction of output.
Miss Hume's essay on Vitamins," based on researches directed by Dr. Harriette Chick at the Lister Institute during the war, is most instructive. No one has ever seen a " vitamine " or " accessory food-factor," but it is something that is necessary. to a healthy diet. Two at least of such factors are recognized ; the absence of one tends to promote beri-beri and the absence of the other encourages scurvy. Some other factor, generally associated with animal fat, is potent against rickets. The anti-beri-beri vitamine is contained in the " germ " or embryo of the wheat grain, which is removed with the bran in all modern processes of wheat-milling. If, therefore, we had to live on white bread alone, we should contract beri-beri, a form of neuritis which has nothing to do with sleeping-sickness. Again, this vitamine is destroyed by the cooking at a high temperature under pressure which is requisite for the sterilizing of tinned foods. Thus it was found during the siege of Kut that many of the British troops, who had to live on white Army bread and tinned meat, developed beri-beri in a more or less acute form. On the other hand, the Indian troops in Kut, who lived on " atta," or very coarsely ground wheat-flour, and "dhal" or pulse of any kind, never had a case of beri-beri. When the British troops ran short of white flour and were given some of the Indian " atta," they ceased to suffer from the disease. Milk, eggs, wholemeal of any kind, peas, beans, lentils, yeast, seem to be specially supplied with this invisible but powerful element. The anti-scorbutic vita mine is more mysterious still. It is abundantly present in fresh oranges and lemons, and fresh cabbage-leaves ; it is present in potatoes, onions, carrots, and other roots and tubers, and in germinated seeds ; it exists also, to a less extent, in fresh meat and milk, but disappears rapidly in the process of cooking or sterilizing, as, for example, in the hay-box. Miss Hume points out that the Indians at Kut, who were free from beri-beri, suffered. severely from scurvy, because most of them, except the Gurkhas, would not touch meat ; when they were persuaded, towards the end of the siege, to eat horse or mule meat, they got better.' She does not believe in the traditional virtue of lime-juice as a preventive of scurvy. It failed in Mesopotamia ; even fresh lime-juice seems to be much weaker than orange or lemon juice.
Miss Hume thinks that the old sailors who praised lime-juice really meant lemon-juice. Another tradition is thus shattered. We must note Miss Hume'S warning that dried vegetables have no value against scurvy. The vitamine, whatever it be, disappears in the drying.
Another fascinating chapter is that by Professor Hickson on " Birds and Insects in Relation to Crops." It is, or should be, fairly well known that many birds are the farmer's best friends. Professor Hickson includes among these friends the starling, the chaffinch, and the rook ; he denounces those County Councils who have instituted a campaign against rooks. For the wood-pigeon and the sparrow he has nothing good to say. But the birds, as destroyers of the insect pests which cost the farmer millions of pounds a year, are probably not to be compared with the insect enemies of these pests. Professor Hickson says, for example, that "if, in this war that we are waging for the protection of our food-crops, the Ichneumons were to make a separate peace with the enemy, we should bo starved into submission in twelve months." He is referring to the insects of the Ichneumonidae family, which destroy " a Very large percentage of some of the most virulent of our insect pests." Here the entomologist comes into his own. Many foolish people have doubtless smiled at the man of science who is content to study insects less attractive than the butterfly or the bee or ant. But entomology ceases to seem trivial when we are told how a certain ichneumon parasite, called ile,soleius tenthredinis, is the deadly enemy of the larch saw-fly, and may, if encouraged; save whole forests from that pest. The parasite has actually been sent from this country to Canada for that purpose. This is a simple instance of the way in which entomology may be brought to bear on agriculture and forestry. The mere application of so-called insecticides is not enough, as any gardener knows. We may be killing the good and the bad insects indiscriminately. Some day, no doubt, the experts will know the precise insect to match against the tvireworm. Perhaps, indeed, the wireworm, like the rook, will prove to be a good fellow after all.
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