by Grant Allen
FOOD AND FEEDING
When a man and a bear meet together casually in an American forest, it makes a great deal of difference, to the two parties concerned at least, whether the bear eats the man or the man eats the bear. We haven’t the slightest difficulty in deciding afterwards which of the two, in each particular case, has been the eater, and which the eaten. Here, we say, is the grizzly that eat the man; or, here is the man that smoked and dined off the hams of the grizzly. Basing our opinion upon such familiar and well-known instances, we are apt to take it for granted far too readily that between eating and being eaten, between the active and the passive voice of the verb edo, there exists necessarily a profound and impassable native antithesis. To swallow an oyster is, in our own personal histories, so very different a thing from being swallowed by a shark that we can hardly realise at first the underlying fundamental identity of eating with mere coalescence. And yet, at the very outset of the art of feeding, when the nascent animal first began to indulge in this very essential animal practice, one may fairly say that no practical difference as yet existed between the creature that ate and the creature that was eaten. After the man and the bear had finished their little meal, if one may be frankly metaphorical, it was impossible to decide whether the remaining being was the man or the bear, or which of the two had swallowed the other. The dinner having been purely mutual, the resulting animal represented both the litigants equally; just as, in cannibal New Zealand, the chief who ate up his brother chief was held naturally to inherit the goods and chattels of the vanquished and absorbed rival, whom he had thus literally and physically incorporated.
A jelly-speck, floating about at his ease in a drop of stagnant water under the field of a microscope, collides accidentally with another jelly-speck who happens to be travelling in the opposite direction across the same miniature ocean. What thereupon occurs? One jelly-speck rolls itself gradually into the other, so that, instead of two, there is now one; and the united body proceeds to float away quite unconcernedly, without waiting to trouble itself for a second with the profound metaphysical question, which half of it is the original personality, and which half the devoured and digested. In these minute and very simple animals there is absolutely no division of labour between part and part; every bit of the jelly-like mass is alike head and foot and mouth and stomach. The jelly-speck has no permanent limbs, but it keeps putting forth vague arms and legs every now and then from one side or the other; and with these temporary and ever-dissolving members it crawls along merrily through its tiny drop of stagnant water. If two of the legs or arms happen to knock up casually against one another, they coalesce at once, just like two drops of water on a window-pane, or two strings of treacle slowly spreading along the surface of a plate. When the jelly-speck meets any edible thing — a bit of dead plant, a wee creature like itself, a microscopic egg — it proceeds to fold its own substance slimily around it, making, as it were, a temporary mouth for the purpose of swallowing it, and a temporary stomach for the purpose of quietly digesting and assimilating it afterwards. Thus what at one moment is a foot may at the next moment become a mouth, and at the moment after that again a rudimentary stomach. The animal has no skin and no body, no outside and no inside, no distinction of parts or members, no individuality, no identity. Roll it up into one with another of its kind, and it couldn’t tell you itself a minute afterwards which of the two it had really been a minute before. The question of personal identity is here considerably mixed.
But as soon as we get to rather larger creatures of the same type, the antithesis between the eater and the eaten begins to assume a more definite character. The big jelly-bag approaches a good many smaller jelly-bags, microscopic plants, and other appropriate food-stuffs, and, surrounding them rapidly with its crawling arms, envelopes them in its own substance, which closes behind them and gradually digests them. Everybody knows, by name at least, that revolutionary and evolutionary hero, the amœba — the terror of theologians, the pet of professors, and the insufferable bore of the general reader. Well, this parlous and subversive little animal consists of a comparatively large mass of soft jelly, pushing forth slender lobes, like threads or fingers, from its own substance, and gliding about, by means of these tiny legs, over water-plants and other submerged surfaces. But though it can literally turn itself inside out, like a glove, it still has some faint beginnings of a mouth and stomach, for it generally takes in food and absorbs water through a particular part of its surface, where the slimy mass of its body is thinnest. Thus the amœba may be said really to eat and drink, though quite devoid of any special organs for eating or drinking.
The particular point to which I wish to draw attention here, however, is this: that even the very simplest and most primitive animals do discriminate somehow between what is eatable and what isn’t. The amœba has no eyes, no nose, no mouth, no tongue, no nerves of taste, no special means of discrimination of any kind; and yet, so long as it meets only grains of sand or bits of shell, it makes no effort in any way to swallow them; but, the moment it comes across a bit of material fit for its food, it begins at once to spread its clammy fingers around the nutritious morsel. The fact is, every part of the amœba’s body apparently possesses, in a very vague form, the first beginnings of those senses which in us are specialised and confined to a single spot. And it is because of the light which the amœba thus incidentally casts upon the nature of the specialised senses in higher animals that I have ventured once more to drag out of the private life of his native pond that already too notorious and obtrusive rhizopod.
With us lordly human beings, at the extreme opposite end in the scale of being from the microscopic jelly-specks, the art of feeding and the mechanism which provides for it have both reached a very high state of advanced perfection. We have slowly evolved a tongue and palate on the one hand, and French cooks and pâté de foie gras on the other. But while everybody knows practically how things taste to us, and which things respectively we like and dislike, comparatively few people ever recognise that the sense of taste is not merely intended as a source of gratification, but serves a useful purpose in our bodily economy, in informing us what we ought to eat and what to refuse. Paradoxical as it may sound at first to most people, nice things are, in the main, things that are good for us, and nasty things are poisonous or otherwise injurious. That we often practically find the exact contrary the case (alas!) is due, not to the provisions of nature, but to the artificial surroundings in which we live, and to the cunning way in which we flavour up unwholesome food, so as to deceive and cajole the natural palate. Yet, after all, it is a pleasant gospel that what we like is really good for us, and, when we have made some small allowances for artificial conditions, it is in the main a true one also.
The sense of taste, which in the lowest animals is diffused equally over the whole frame, is in ourselves and other higher creatures concentrated in a special part of the body, namely the mouth, where the food about to be swallowed is chewed and otherwise prepared beforehand for the work of digestion. Now it is, of course, quite clear that some sort of supervision must be exercised by the body over the kind of food that is going to be put into it. Common experience teaches us that prussic acid and pure opium are undesirable food-stuffs in large quantities; that raw spirits, petroleum, and red lead should be sparingly partaken of by the judicious feeder; and that even green fruit, the bitter end of cucumber, and the berries of deadly nightshade are unsatisfactory articles of diet when continuously persisted in. If, at the very outset of our digestive apparatus, we hadn’t a sort of automatic premonitory adviser upon the kinds of food we ought or ought not to indulge in, we should naturally commit considerable imprudences in the way of eating and drinking — even more than we do at present. Natural selection has therefore provided us with a fairly efficient guide in this respect in the sense of taste, which is placed at the very threshold, as it were, of our digestive mechanism. It is the duty of taste to warn us against uneatable things, and to recommend to our favourable atten
tion eatable and wholesome ones; and, on the whole, in spite of small occasional remissness, it performs this duty with creditable success.
Taste, however, is not equally distributed over the whole surface of the tongue alike. There are three distinct regions or tracts, each of which has to perform its own special office and function. The tip of the tongue is concerned mainly with pungent and acrid tastes; the middle portion is sensitive chiefly to sweets and bitters; while the back or lower portion confines itself almost entirely to the flavours of roast meats, butter, oils, and other rich or fatty substances. There are very good reasons for this subdivision of faculties in the tongue, the object being, as it were, to make each piece of food undergo three separate examinations (like ‘smalls,’ ‘mods,’ and ‘greats’ at Oxford), which must be successively passed before it is admitted into full participation in the human economy. The first examination, as we shall shortly see, gets rid at once of substances which would be actively and immediately destructive to the very tissues of the mouth and body; the second discriminates between poisonous and chemically harmless food-stuffs; and the third merely decides the minor question whether the particular food is likely to prove then and there wholesome or indigestible to the particular person. The sense of taste proceeds, in fact, upon the principle of gradual selection and elimination; it refuses first what is positively destructive, next what is more remotely deleterious, and finally what is only undesirable or over-luscious.
When we want to assure ourselves, by means of taste, about any unknown object — say a lump of some white stuff, which may be crystal, or glass, or alum, or borax, or quartz, or rocksalt — we put the tip of the tongue against it gingerly. If it begins to burn us, we draw it away more or less rapidly with an accompaniment in language strictly dependent upon our personal habits and manners. The test we thus occasionally apply, even in the civilised adult state, to unknown bodies is one that is being applied every day and all day long by children and savages. Unsophisticated humanity is constantly putting everything it sees up to its mouth in a frank spirit of experimental inquiry as to its gustatory properties. In civilised life we find everything ready labelled and assorted for us; we comparatively seldom require to roll the contents of a suspicious bottle (in very small quantities) doubtfully upon the tongue in order to discover whether it is pale sherry or Chili vinegar, Dublin stout or mushroom ketchup. But in the savage state, from which, geologically and biologically speaking, we have only just emerged, bottles and labels do not exist. Primitive man, therefore, in his sweet simplicity, has only two modes open before him for deciding whether the things he finds are or are not strictly edible. The first thing he does is to sniff at them; and smell, being, as Mr. Herbert Spencer has well put it, an anticipatory taste, generally gives him some idea of what the thing is likely to prove. The second thing he does is to pop it into his mouth, and proceed practically to examine its further characteristics.
Strictly speaking, with the tip of the tongue one can’t really taste at all. If you put a small drop of honey or of oil of bitter almonds on that part of the mouth, you will find (no doubt to your great surprise) that it produces no effect of any sort; you only taste it when it begins slowly to diffuse itself, and reaches the true tasting region in the middle distance. But if you put a little cayenne or mustard on the same part, you will find that it bites you immediately — the experiment should be tried sparingly — while if you put it lower down in the mouth you will swallow it almost without noticing the pungency of the stimulant. The reason is, that the tip of the tongue is supplied only with nerves which are really nerves of touch, not nerves of taste proper; they belong to a totally different main branch, and they go to a different centre in the brain, together with the very similar threads which supply the nerves of smell for mustard and pepper. That is why the smell and taste of these pungent substances are so much alike, as everybody must have noticed, a good sniff at a mustard-pot producing almost the same irritating effects as an incautious mouthful. As a rule we don’t accurately distinguish, it is true, between these different regions of taste in the mouth in ordinary life; but that is because we usually roll our food about instinctively, without paying much attention to the particular part affected by it. Indeed, when one is trying deliberate experiments in the subject, in order to test the varying sensitiveness of the different parts to different substances, it is necessary to keep the tongue quite dry, in order to isolate the thing you are experimenting with, and prevent its spreading to all parts of the mouth together. In actual practice this result is obtained in a rather ludicrous manner — by blowing upon the tongue, between each experiment, with a pair of bellows. To such undignified expedients does the pursuit of science lead the ardent modern psychologist. Those domestic rivals of Dr. Forbes Winslow, the servants, who behold the enthusiastic investigator alternately drying his tongue in this ridiculous fashion, as if he were a blacksmith’s fire, and then squeezing out a single drop of essence of pepper, vinegar, or beef-tea from a glass syringe upon the dry surface, not unnaturally arrive at the conclusion that master has gone stark mad, and that, in their private opinion, it’s the microscope and the skeleton as has done it.
Above all things, we don’t want to be flayed alive. So the kinds of tastes discriminated by the tip of the tongue are the pungent, like pepper, cayenne and mustard; the astringent, like borax and alum; the alkaline, like soda and potash; the acid, like vinegar and green fruit; and the saline, like salt and ammonia. Almost all the bodies likely to give rise to such tastes (or, more correctly, sensations of touch in the tongue) are obviously unwholesome and destructive in their character, at least when taken in large quantities. Nobody wishes to drink nitric acid by the quart. The first business of this part of the tongue is, therefore, to warn us emphatically against caustic substances and corrosive acids, against vitriol and kerosene, spirits of wine and ether, capsicums and burning leaves or roots, such as those of the common English lords-and-ladies. Things of this sort are immediately destructive to the very tissues of the tongue and palate; if taken incautiously in too large doses, they burn the skin off the roof of the mouth; and when swallowed they play havoc, of course, with our internal arrangements. It is highly advisable, therefore, to have an immediate warning of these extremely dangerous substances, at the very outset of our feeding apparatus.
This kind of taste hardly differs from touch or burning. The sensibility of the tip of the tongue is only a very slight modification of the sensibility possessed by the skin generally, and especially by the inner folds over all delicate parts of the body. We all know that common caustic burns us wherever it touches; and it burns the tongue only in a somewhat more marked manner. Nitric or sulphuric acid attacks the fingers each after its own kind. A mustard plaster makes us tingle almost immediately; and the action of mustard on the tongue hardly differs, except in being more instantaneous and more discriminative. Cantharides work in just the same way. If you cut a red pepper in two and rub it on your neck, it will sting just as it does when put into soup (this experiment, however, is best tried upon one’s younger brother; if made personally, it hardly repays the trouble and annoyance). Even vinegar and other acids, rubbed into the skin, are followed by a slight tingling; while the effect of brandy, applied, say, to the arms, is gently stimulating and pleasurable, somewhat in the same way as when normally swallowed in conjunction with the habitual seltzer. In short, most things which give rise to distinct tastes when applied to the tip of the tongue give rise to fainter sensations when applied to the skin generally. And one hardly needs to be reminded that pepper or vinegar placed (accidentally as a rule) on the inner surface of the eyelids produces a very distinct and unpleasant smart.
The fact is, the liability to be chemically affected by pungent or acid bodies is common to every part of the skin; but it is least felt where the tough outer skin is thickest, and most felt where that skin is thinnest, and the nerves are most plentifully distributed near the surface. A mustard plaster would probably fail to draw at all on one’s hee
l or the palm of one’s hand; while it is decidedly painful on one’s neck or chest; and a mere speck of mustard inside the eyelid gives one positive torture for hours together. Now, the tip of the tongue is just a part of one’s body specially set aside for this very object, provided with an extremely thin skin, and supplied with an immense number of nerves, on purpose so as to be easily affected by all such pungent, alkaline, or spirituous substances. Sir Wilfrid Lawson would probably conclude that it was deliberately designed by Providence to warn us against a wicked indulgence in the brandy and seltzer aforesaid.
At first sight it might seem as though there were hardly enough of such pungent and fiery things in existence to make it worth while for us to be provided with a special mechanism for guarding against them. That is true enough, no doubt, as regards our modern civilised life; though, even now, it is perhaps just as well that our children should have an internal monitor (other than conscience) to dissuade them immediately from indiscriminate indulgence in photographic chemicals, the contents of stray medicine bottles, and the best dried West India chilies. But in an earlier period of progress, and especially in tropical countries (where the Darwinians have now decided the human race made its first début upon this or any other stage), things were very different indeed. Pungent and poisonous plants and fruits abounded on every side. We have all of us in our youth been taken in by some too cruelly waggish companion, who insisted upon making us eat the bright, glossy leaves of the common English arum, which without look pretty and juicy enough, but within are full of the concentrated essence of pungency and profanity. Well, there are hundreds of such plants, even in cold climates, to tempt the eyes and poison the veins of unsuspecting cattle or childish humanity. There is buttercup, so horribly acrid that cows carefully avoid it in their closest cropped pastures; and yet your cow is not usually a too dainty animal. There is aconite, the deadly poison with which Dr. Lamson removed his troublesome relatives. There is baneberry, whose very name sufficiently describes its dangerous nature. There are horse-radish, and stinging rocket, and biting wall-pepper, and still smarter water-pepper, and worm-wood, and nightshade, and spurge, and hemlock, and half a dozen other equally unpleasant weeds. All of these have acquired their pungent and poisonous properties, just as nettles have acquired their sting, and thistles their thorns, in order to prevent animals from browsing upon them and destroying them. And the animals in turn have acquired a very delicate sense of pungency on purpose to warn them beforehand of the existence of such dangerous and undesirable qualities in the plants which they might otherwise be tempted incautiously to swallow.
