The Great Food Question

( Originally Published 1909 )

FOR us to show how important the food question is to life may remind some of Artemus Ward, who, in an illustrated lecture on his travels, drew the particular attention of his audience to the fact, shown by his picture, that the highest part of a mountain is its top! That earthly life depends on food is equally clear and in-disputable. But after all, things most commonplace may hide behind them some of the greatest and deepest mysteries of the world. Thus the ancient Greeks, after carving an Apollo Belvedere out of stone, placed the choicest viands and the finest wines before this statue of the god on his feast days. They well knew that this procedure was altogether a pious make-believe. However life-like it may be, nothing but what is really living can be fed. Nor were the old Egyptians different when they surrounded their dead mummies with articles of food and drink for the spirits which hovered about them. Their mummies did live once, and why not let them eat and drink as they did before? The answer is the same : nothing without life can be fed.

Darwin indeed made the strife over the great Food Question about the only creator needed for coiling living forms into existence, as Nature, he said, practically put the same question to all, namely, how to eat or keep from being eaten. It was the food question which set Natural Selection to shape the lion so that he would be well hid while waiting for his living meal on a gazelle, and in turn made the legs of the gazelle good for running away from him.

But Darwin builded better than he knew by making the food question such a great one in the process of life, for modern physiology has extended its scope from the bodies of animals to each cell in their bodies. In this undreamed of extension, Natural Selection is simply swamped, or rather it is like emptying a little brook into a sea. For now we find that the different cells of the metazoic body which had first given up their independence for interdependence, as we have described, on the food question re-assert their original autonomy. Every cell of the body insists on having its own diet. They all must have food or they would die of starvation. They can grow and be themselves in shape and in function only according to what they feed upon. But a muscle cell cannot live on what a bone cell lives on, nor will the simple fare which suffices for a cartilage cell be accepted by a nerve cell which demands the most elaborate and varied menu of anything living. They all get what they want from that wonderfully composite, all-nourishing blood, but they carefully select just what they want and reject what they do not want. The cells which make hairs never allow any ingredients of the bile, which liver cells make, to enter them. And so on to the end. No such multi-form discrimination meets us anywhere as in this realm of life.

This very particular selection by body cells of their food stuffs, is one of the great puzzles of biologists. Many of them have come to the conclusion that the cells know so well what they ought to have that they must be actually endowed with consciousness and choose accordingly. Professor G. Bunge * of the University of Basle quotes in illustration the observations of Cienkowski on a minute ameba called Vampyrella, that will take but one form of food, which is a particular variety of algae, the Spirogyra. The Vampyrella creeps along among numbers of other algae until it meets with a Spirogyra, to which it then affixes itself and perforating its cellulose coat it sucks in the contents of its cell, and then travels in quest of the next Spirogyra, to repeat the process. Cienkowski never saw the Vampyrella attack any other class of algae, or take up any other substance. Vaucherae, Edogoniae, etc., purposely placed before it, were always rejected. " The behavior of these single-celled creatures in their search after food, and in their method of absorbing it, is so remarkable," says Cienkowski, " that one can hardly avoid the conclusion that the acts are those of conscious beings."

We may say that similar discriminating performances are shown by certain vampires in our money markets, who show no interest in anybody except in those who own stocks and bonds. To these they-attach themselves and soon transfer all their stocks to their own pockets ere they pass to the next victim. " But," Professor Bunge continues, " just as the Vampyrella picks out the Spirogyra from amongst all other alga, so do the epithelial cells of our intestines select the fat drops and reject the pigment granules. We know that these intestinal epithelial cells prevent the absorption of a whole series of poisons, in spite of the fact that the latter are easily soluble in the gastric and intestinal juices.

. . Also in all secreting cells we find the same mysterious power of selection."

Similar doctrines attributing reasoning power to the cells, and thereby to the lower animals and plants, all based on the food question, are advanced by such biologists as Delfino, Cope, Pauly, and Firanci, while Sir Francis Darwin, son of Charles Darwin, in his inaugural address as President of the British Association of Science, at Dublin, 1908, says : " It is impossible to know whether or not plants are conscious; but it is consistent with the doctrine of continuity that in all living things there is something psychic, and if we accept this point of view, we must believe that in plants there exists a faint copy of what we know as consciousness in our-selves."

But at this point we must part company with these learned observers. Though admitting that life is fundamentally one in both plant and animal, yet in common with most of our fellows we regard consciousness as the sole attribute of certain sentient nervous centres, and hence cannot but regard those whose steps logically lead them to conscious potatoes and cabbage heads as well on the way to absurdity.

Quite another aspect of this problem in cell life, and one which apparently affords considerable support to the anti-vitalists, is presented by some researches in medical science, on the subject of Immunity. To determine why a single attack of some infectious diseases renders that person immune against a second attack of the same, or why some persons seem to have a natural immunity against infections in general, while others are very susceptible to them, or why some infections confer only temporary immunity or none at all against their recurrence, are certainly questions of much practical importance. Their investigation has led recently to some of the most abstruse speculations in the history of medicine. Now theories are valuable in proportion to their number of explanations, and as no demonstrated facts long remain isolated in science, so one largely accepted theory of the mechanism of immunity, called Professor Ehrlich's side chain theory, is found ultimately to have important relations to our subject of cell assimilation of food, or in other words, how it is that food feeds us. It is difficult, however, to lead the general reader along the intricate lines of this hypothesis with-out giving him a headache, and so we will only attempt a necessarily imperfect outline of it, by beginning with a rough illustration. If the reader has ever had the pleasure, or to some the horror, of seeing that fresh-water polyp called a hydra fusca in a water receptacle which allows him to be seen with a low magnifying power, he then looks like a great octopus swinging his ugly arms, all covered with contractile nodules, about in the water. A careful inspection shows that he holds several long, fine fish-lines at the end of each of his arms, these lines terminating in a little round poison sack surmounted by a perfect barb, thus, J Swimming actively about are many little white crustaceans called daphnes, wholly unmindful of the hydra, when suddenly one of them is seen to swim no longer. Watching this now motionless daphne, it is found that one of the fatal barbs has struck him and that he is motionless because paralyzed by the poison from that little sack. Then the hydra pulls the crustacean in as a fisher-man would a trout he had hooked, and soon the hydra eats him up. Now those living cells in our blood called the white corpuscles are capable of throwing Out what are termed their pseudopodia: these have been seen to seize invading bacteria and to draw them in to be devoured and digested by the white cell. This phenomenon forms the basis of Metchnikoff's phagocytic or cell-eating theory of immunity. But some bacteria kill, not by themselves entering the blood but by their first securing a lodgment in some part where they stay, generating a virulent soluble poison which poison, and not the bacilli, is then absorbed into the blood. This is the case with the tetanus or lock-jaw bacillus, and hence a tetanus anti-toxin must save a patient with lockjaw in a different way than by Metchnikoff's phagocytes. With Ehrlich's side chain theory, therefore, our hydra illustration would have to be modified into imagining the chains of nodules on the hydra's arms as themselves shooting out lines of attraction which arrest the poisons as they pass in the blood and draw them in to be incorporated into the nodule.

But these lines of attraction must be purely chemical in their nature, or in other words lines of chemical affinity for ingredients in the poisons, and the phenomenon itself, therefore, has received the name of chemio-taxis, or chemical drawing. Therefore on this principle every cell of the body when it draws its food from the lymph which comes to it from the blood, selects what it wants by chemio-taxis, that is, by a power or property which is not essentially different in nature from other chemical affinities. Therefore, our supposedly living attribute of nutrition by feeding turns out after all to be a thing of chemistry.

Admitting all this to be true, yet chemio-taxis no more explains life itself than anything else does. It is life which produces chemio-taxis, and not chemio-taxis which produces life. Our former comparison still holds that it is not smoke which causes fire, but it is fire which causes smoke. Life produces all kinds of chemical things, with this important difference, that organic chemistry, i.e., that which is produced by living agencies, is vastly more complex in its processes than inorganic chemistry. A molecule of water, for example, has only three atoms in its composition, two of hydrogen, and one of oxygen, but a molecule of cane-sugar has forty-five atoms, and, moreover, these atoms are so differently arranged in different sugars that a painstaking authority has written five volumes on the sugars alone, and is not through with them yet.

Whatever else, therefore, may be said of organic chemistry, this is certain, that something enters into its processes which is not found in any other chemistry, that something making its products far removed from all other chemical components in the makeup of their molecules.

But if each kind of cell in the body has its own chemistry, we may well be staggered at the infinite number of shapes and forms which vital chemistry assumes. Thus we must have a different and special chemio-taxis for the cell which is helping to make a toe nail from one which is building up a centre for sight in the brain cortex, and then untold thousands more of varying kinds of chemio-taxis the body over.

It is the frequent recurrence of such embarrassing conclusions which is making many of the younger biologists weary with all physico-chemical explanations of life. As J. E. Haldane, M.D., F.R.S., Professor of Physiology in the University of Oxford, remarks : "As a matter of fact, the physico-chemical theory of life has not worked in the past and can never work. Those who aim at physico-chemical explanations of life are simply running their heads at a stone wall, and can only expect sore heads as a consequence."