Part 7

the seven days seventy-seven cents! If we contrast this figure with the amounts generally paid for average nourishment for a like period of time, there is certainly food for serious thought. Mr. Fletcher avers that he has followed his present plan of living for nearly five years; he usually takes two meals a day; has been led to a strong liking for sugar and carbohydrates in general and away from a meat diet; is always in perfect health, and is constantly in a condition of fitness for work. He practises thorough mastication, with more complete insalivation of the food (liquid as well as solid) than is usual, thereby insuring more complete and ready digestion and a more thorough utilisation of the nutritive portions of the food.

In view of these results, are we not justified in asking ourselves whether we have yet attained a clear comprehension of the real requirements of the body in the matter of daily nutriment? Whether we fully comprehend the best and most economical method of maintaining the body in a state of physiological fitness? The case of Mr. Fletcher, just described; the results noted in connection with certain Asiatic peoples; the fruitarians and _nut_arians in our own country recently studied by Professor Jaffa, of the University of California; all suggest the possibility of much greater physiological economy than we as a race are wont to practise. If these are merely exceptional cases, we need to know it; but if, on the other hand, it is possible for mankind in general to maintain proper nutritive conditions on dietary standards far below those now accepted as necessary, it is time for us to ascertain that fact. For, if our standards are now unnecessarily high, then surely we are not only practising an uneconomical method of sustaining life, but we are subjecting ourselves to conditions the reverse of physiological, and which must of necessity be inimical to our well-being. The possibility of more scientific knowledge of the natural requirements of a healthy nutrition is made brighter by the fact that the economic results noted in connection with our metabolism examination of Mr. Fletcher is confirmatory of similar results obtained under the direction and scrutiny of Sir Michael Foster at the University of Cambridge, England, during the autumn and winter of last year; and by Dr. Ernest Van Someren, Mr. Fletcher’s _collaborateur_, in Venice, on subjects of various ages and of both sexes, some account of which has already been presented to the British Medical Association and to the International Congress of Physiologists at its last meeting at Turin, Italy. At the same time emphasis must be laid upon the fact that no definite and positive conclusions can be arrived at, except as the result of careful experiments and observations on many individuals covering long periods of time. This, however, the writer hopes to do in the very near future, with the coöperation of a corps of interested observers.

The problem is far-reaching. It involves not alone the individual, but society as a whole, for beyond the individual lies the broader field of the community, and what proves helpful for the one will eventually react for the betterment of society, and for the improvement of mankind in general.

INTRODUCTION TO DR. HARRY CAMPBELL’S CONTRIBUTION ON THE IMPORTANCE

OF MASTICATION

[Since the publication of Van Someren’s paper, “Was Luigi Cornaro Right?”, read before the British Medical Association, and reprinted elsewhere in this volume, much more attention has been given to the study of mastication than had been previously reported. Mr. Gladstone’s advice to his children, which was commonly current and was repeated whenever mastication was mentioned, was usually accompanied and met by an amused smile that showed that the full importance of better mouth-treatment of food was not appreciated. _Glutton or Epicure_, a little book by the present writer, published in 1898, insisted on thorough use of the functions of the mouth in alimentation but did not go into the anatomical, physiological and dental details.

Dr. Harry Campbell of Northwest London Hospital has performed this latter service to science and humanity, with splendid carefulness, and must have devoted much time and study to the collection of evidence and suggestion which is given here following in full, reprinted from the _London Lancet_.

The authors acknowledge with much gratitude, the courteous permission of both Dr. Campbell and of the editor of the _Lancet_, to reprint all four articles which composed the series.

In our own study of the subject of mouth-treatment of food we have been led to give more credit to the chemical feature of preparation than Dr. Campbell yet attributes to the chemical side of the problem. Comminution of hard food is of first importance, undoubtedly, but insalivation and neutralisation or alkalinisation are, seemingly, much more easily and quickly accomplished in the mouth than farther on in the alimentary canal. The intestines _can_ do all in the way of digestion, even if the mouth and stomach are passed and their assistance in the digestive process is entirely neglected, but it is done at tremendous disadvantage in the supplementary digestive tract of the intestines. We have proven the economy of letting the mouth do _all it can_, by the insalivation (sipping and tasting) of liquids that have taste up to the point of compulsory swallowing (a sucking-up by the Swallowing Impulse which naturally occurs in the course of treatment in the mouth if not fought against too strongly). If Dr. Campbell will extend his observations to liquids, say milk, and for a sufficiently long time to measure results by continued economy of assimilation and saving of solid excreta, he will find that it pays to let the mouth do all it can do, and that while it _cannot do too much_ it _may do too little_. The natural instincts of the mouth, or those that attach to the mouth, become much more discriminating also if exercised on liquids as well as on solids. This they do not learn to do so well if sapid liquids are habitually rushed past their field of discrimination.

Taste enjoyed in the mouth is good, and a good part of the pleasure of living comes from taste gratification, but taste that returns from the stomach and is belched by eructation or is lingeringly reminiscent in the mouth or nose is indicative of indigestion.

Hence it is better to dissipate taste in the mouth, which is the sole region of taste. Spirits tasted into absorption in this way leave no odour upon the breath, and asparagus munched and tasted to the limit in the mouth, carries no odour to the urine. Even the stale and disagreeable odour of onion or garlic can be neutralised by saliva and killed in the mouth.

It is extremely difficult to get observers to practise tasting taste out of liquids as the wine tasters do, and as the tea tasters _have to do or die_; or, at least, become useless in their profession. Once the efficacy of the liquid-tasting precaution in digestion is understood, however, to swallow anything but pure water without tasting it into absorption produces a shock. This care becomes instinctive quite easily and regulates itself automatically. It is also a distinct gain to the gustatory possibilities, which are very limited at best.

When the body will tolerate spirits tasted into it--not poured into it--at all, which is not often when the nutrition is normal (only in damp or cold weather, as a general thing, and then in the case of the writer only at rare intervals, say two or three times a year), the spirit will mix quickly with the saliva and become neutralised sufficiently to excite the Swallowing Impulse. Continue sipping the spirit for a time and you will note that there comes a point where the saliva and the spirit do not mix, do not neutralise; the mouth becomes unduly full of liquid without any relaxation or invitation of the Swallowing Impulse; and the really instinctive inclination will be to _spit it out_. It is a clear indication that the body-_toleration_ has been fully taxed; there is no longer any bodily need for alcohol--in fact, there is no longer natural toleration--and the secretion sent down into the mouth is evidently mucous for a washing-out process, and is not alkaline saliva for assisting in a utilisation function.

It is quite uncanny to observe the nicety of mouth-discrimination and the consistency of it as related to similar substances under similar conditions, if one learn to read it with precision and intelligence.

With increased ease of digestion, which comes with more thorough attention to solid foods alone, the ordinary observer will think that he has accomplished the whole of the possible benefit. It is only when he gives sufficient time to liquids also, to get the added delight and relief that salivary respect of them brings, that the whole of the beneficence of mouth-service is realised. Follow this discrimination and care to a comparative measurement of the waste of digestion, the solid excreta, and note the increased proportionate gain in assimilation and the value of the economy will be appreciated. Try the different treatments on milk for a month; fifteen days with drinking and fifteen days insalivating (sipping and tasting) the milk to the limit, and keep account of quantity of intake required to satisfy appetite and maintain body-weight; and also note carefully the condition and quantity of the fæces. In the one case you will find the waste to be _fæces_ indeed, and unmistakably worthy of the name; but in the case of sipping, tasting and insalivating the milk to the full satisfaction of the appetite, the _digestion-ash_ will assume quite a different amount and character and deserve a change of name. The proportions of the saving in our own experiments have approximated the difference between three and ten; that is, on a reduction of only one-third the quantity of food commonly ingested, but fully satisfying the sipping and tasting appetite, the quantity of solid excreta was only one-tenth of the other and of quite a different character, æsthetically considered.

While these suggestions do not discredit or affect the value of the purely mechanical side of the treatment as given by Dr. Campbell, and are not intended to be controversial, they are ventured as an amendment to be worked out in regard to liquids, which are, in fact, only an extreme of the pultaceous foods against which Dr. Campbell warns us as being subtly dangerous.

There is another point in our experiences and observations of the largest importance that may appropriately be introduced here: The treatment of all liquids in the manner suggested prevents intemperance of drinking as effectively as it does intemperance of eating.

When food is filtered into the body after having become liquified and made alkaline, or, at least neutral, by saliva, the appetite is given a chance to measure the needs of the body and to discriminate against excess. As soon as the point of complete saturation of any one deficiency is reached, the appetite is cut off, as short as possible to imagine, with no indication of stomach fullness. It will welcome a little of proteid in beans, cheese, eggs, or in some other of its richer forms, and then turn to sugar or fat in some of their numerous forms. Thirst for water will assert itself for a moment, sometimes asking but for a drop and again for a full glass, and afterwards, when near the point of complete saturation, appetite will hesitate for a moment, as if searching around for some rare substance, and may find its final satisfaction in a single spoonful of a sweet or a sip of something in sight.

The appetite satisfied by the infiltering process is a sweetly appeased appetite, calm, rested, contented, normal. There is no danger from the flooding of intemperance, for there is not even toleration of excess either of more food or of more drink, and this contented appetite will remain in the condition of contentment until another need has really been earned by evaporation or destructive katabolism.

In the teaching of this physiology and psychology of alimentation to the children of England, lies the only true solution of the drink question, which is now the curse of the nation.

Dr. Campbell has made such a splendid case for the mechanical side of mouth work, that it is the hope of the writer that he will give equally careful consideration to the chemical and psychological sides, and in a completeness of observation render inestimable service to his country, to science, and humanity. A decade of trial on the inmates of an infant orphan asylum will show the possibilities for the nation in a single generation, if broadly applied. It might lead to an effective intemperance, inhibition, or quarantine, and that is all any nation needs of advantage to make it independent of the world and truly great.—HORACE FLETCHER.]

OBSERVATIONS ON MASTICATION

BY HARRY CAMPBELL, M.D., F.R.C.P. (Lond.)

_Physician to the Northwest London Hospital_

[London _Lancet_, July 11, 18, 25, and August 8, 1903]

SECTION I. From _London Lancet_, July 11, 1903

THE EFFECTS OF MASTICATION

The primary object of mastication is to break up the food so as (1) to facilitate the swallowing of it, and (2), still more important, to insure its intimate admixture with the digestive juices, not only within the mouth, but throughout the entire digestive tract. Mastication has, however, other important and far-reaching effects. Thus it promotes the flow of saliva and, when properly performed, secures a due insalivation of the food; it increases the quantity of alkaline saliva passing into the stomach; it stimulates the heart and circulation; and it finally influences the nutrition of the jaws and their appendages by stimulating the local blood and lymph circulation. Now to consider these various objects and effects of mastication.

_Mastication facilitates swallowing._--Many foods cannot be swallowed without first going through some preparation in the mouth. Soft, moist, pultaceous foods, such as milk pudding and porridge, can be and often, indeed, are swallowed with little or no preliminary chewing. On the other hand, it is a mechanical impossibility to swallow large lumps of tough food, or very dry food, even though, like flour, it be in a finely divided state. Dry food needs first to be well moistened; and it is not surprising that it promotes a more abundant flow of saliva than moist food, though the secretion thus excited may be poor in ferment. Hence it follows that if we desire to give foods which compel mastication, they should be tough or dry. On the whole, vegetable foods necessitate more thorough mastication than animal. The carnivora can scarcely be said to masticate at all the flesh which they consume; they simply tear off portions, and forthwith swallow them whole. Cooked flesh, however, does require mastication, owing to the coagulation of its proteids. The herbivora, on the other hand, unlike the carnivora, have to subject their food to considerable mastication before it can be swallowed; but they generally masticate it far more than is needful to render swallowing mechanically possible, as is exemplified in the act of rumination, the object here being to facilitate the admixture of the digestive juices with the food.

According to Van Someren, if the habit of masticating efficiently is once acquired, the food is not swallowed before it is converted into the liquid state, the swallowing of unmasticated lumps being effectually prevented by a pharyngeal reflex.

_Mastication, by breaking the food up into small particles, enables it to be brought into intimate contact with the digestive juices._--Such comminution is especially needful in the case of raw vegetable foods of the tougher kind, in order to break up their cellulose framework, and to set free the contained starch, proteids, and fats. Foods of this kind, unless masticated, yield practically no nutriment to the organism. I cannot too strongly emphasise the fact that before man learned to break up the cellulose framework of his vegetable food by cooking he was compelled to subject it to laborious mastication. But, while thorough comminution is especially needed for vegetable food when raw, it is also needed for many cooked forms of it also,--as, for example, solid batter pudding and new underbaked bread, heavy lumps of which, passing into the stomach, may seriously hamper the work of that organ. Such substances are indigestible essentially by virtue of their impermeability to the digestive juices, and they gain in digestibility in proportion as they are comminuted. The indigestibility of new bread would appear to be wholly due, not to any peculiarity of chemical composition, but to its tendency to elude the teeth and form a sodden mass impermeable to the digestive juices, while the more powdery stale bread is more easily broken up both in the mouth and within the stomach. Cabbage, again, owes its indigestibility to the fact that it is allowed to pass into the stomach in large masses, while the well-known digestibility of cauliflower and minced spinach is due to the fineness of their division; were cabbage as finely minced as spinach usually is it would be equally digestible.

Turning now to animal food it has to be remarked that while in the raw state it may be readily digestible with little or no previous mastication, since massive pieces of it are readily attacked by the digestive juices, the like is much less true of animal food the proteids of which have been coagulated and rendered less permeable by cooking. Large lumps of hard-boiled egg or overdone meat, for instance, may obstinately resist gastric digestion; indeed, as with vegetable so with animal foods, their relative digestibility depends more upon physical consistence than chemical composition; beef is generally more indigestible than mutton and pork or veal than either, not so much by virtue of chemical composition as of physical consistence; the indigestibility of cheese illustrates the same truth; the individual nutritive ingredients of this substance--the proteids and fats--are not in themselves indigestible; casein in the form of protein or plasmon is known to be easy of digestion, and butter is one of the most digestible of fats; but in cheese the two are welded together into a comparatively impermeable mass, which is apt to escape comminution by the teeth and to pass down into the stomach in the form of solid lumps. A plain, wholesome cheese well masticated or intimately mixed with other foods, as in macaroni cheese, is quite easily digested by the majority.

I do not, of course, deny the influence of the chemical factor. Undoubtedly food may disturb digestion by virtue of its chemical composition, apart altogether from its physical characters; thus, while cooked goose-fat sets up violent irritation in some, others cannot tolerate eggs in any shape or form, and innumerable idiosyncrasies in respect of special articles of diet are met with which are essentially referable to chemical composition; but making due allowance for this chemical influence there can, I think, be little doubt that the digestibility of the more common articles of diet, both animal and vegetable, depends in the main upon their physical constitution, _all of them tending to be equally digestible when reduced to the same degree of comminution_. This, if true, is, I need scarcely say, a fact of the greatest practical importance, for it amounts to this: that we may often allow to those with very weak digestions foods which are generally considered indigestible, provided that they be thoroughly comminuted, whether by mastication or artificial means.

_Mastication promotes the flow of saliva and the insalivation of the food._--The more efficiently food is masticated the greater is the salivary flow, and the more intimately is it mixed with the saliva, or, as we say, insalivated. The saliva has apparently no effect on fats; whether it acts on proteids seems more doubtful, though by some authorities the penetration of these by the alkali of this fluid is said to aid in their subsequent digestion; on starch, however, the saliva acts very potently, and hence mastication plays a special

## part in promoting the digestion of starchy foods. Indeed, if only

mastication be persisted in long enough, starch may be wholly converted into maltose within the mouth, and it need scarcely be said that it is better for the individual himself to manufacture his maltose in this way than that he should take it ready made for him in the form of one of the many “malt extracts” on the market. Patients are often forbidden starchy food, while they are allowed the maltose which they can quite well manufacture in their own mouths. Provided they be sufficiently insalivated, there are few starchy foods which are indigestible, not even excepting the proverbially indigestible new potato. These remarks are especially applicable to children, as will be more particularly insisted on later.

_Mastication increases the amount of alkaline saliva passing into the stomach_, and this not only prolongs the period of starch digestion within this organ but, by its influence upon the reaction of the gastric contents, influences all the digestive processes taking place there. I shall have occasion to point out later that a deficient supply of alkaline saliva in the stomach predisposes to certain forms of indigestion.

_Mastication acts reflexly upon the stomach._--It is now known that the act of mastication influences the stomach reflexly, promoting the flow of gastric juice and thus preparing the stomach for the entrance of food into it. If the œsophagus of a dog is cut so as to allow the swallowed food to escape instead of passing into the stomach, it is found that the mastication of food causes a considerable flow of gastric juice. Food introduced into the stomach unaccompanied by mastication is less effective in promoting the gastric flow. It is probable that the influence of mastication on the flow of gastric juice is largely produced through the medium of psychic influences, for the more efficient the mastication the more is the sense of taste affected.

_Mastication stimulates the heart and so promotes the general circulation._--This stimulating action may be partly due to its local

## action on the flow of blood and lymph in the jaws and accessory parts,

and partly to a reflex influence, but whatever the explanation there can be no doubt of the fact. Hence the mere chewing of a non-nutritive substance, such as gum arabic, is stimulating, and, doubtless, the stimulating effects induced by the chewing of such articles as tobacco and betel are largely to be explained in this way.

THE INFLUENCE OF MASTICATION ON THE JAWS AND ADJACENT STRUCTURES

This subject is of such importance that it needs to be dealt with in some detail. By “adjacent structures” I mean the masticatory muscles, tongue, teeth, salivary glands, the nasal passages and sinuses pertaining thereto, the naso-pharynx, soft palate, and tonsils.

_The muscles of mastication._--Let me at the outset draw attention to certain anatomical points, in connection with the muscles of mastication. These are (_a_) their massiveness; (_b_) the very close relation of the pterygoids to the naso-pharynx; and (_c_) the outward direction of the pterygoids.

(_a_) It is not until one studies the muscles of mastication closely that one comes to realise their massiveness. Their large size, in relation to the bony structures in connection with them, is well shown in a vertical transverse section of the head carried through the ascending ramus of the mandible[7] (see Fig. 1). It is evident that the functional activity of so large a mass of muscle tissue cannot but exercise considerable influence on the nutrition of the neighbouring parts.

[Illustration:

FIGURE 1.--Vertical transverse (slightly oblique) section through the head on a level with the epiglottis. The massiveness of the system of masticatory muscles is apparent.]