An essay concerning the nature of aliments: and the choice of them, according to the different constitutions of human bodies. ... By John Arbuthnot, ...

CHAP. I.

Observations drawn from the Altera|tions which the Aliment undergoes in its passage into the Blood.

PROP. I.

MASTICATION is a very necessary Preparation of solid Aliment, without which there can be no good Digestion. By chewing, solid Aliment is divided into small

Parts; in a human Body, there is no other Instrument to perform this Action, but the Teeth. By the Action of chewing, the Spittle and Mucus is squeez'd from the Glands, and mix'd with the Aliment, which Action if it be long continued, will turn the Aliment into a sort of Chyle. The Spittle is an active Liquor, immedi|ately deriv'd from the arterial Blood. It is saponaceous, as appears by its froathing, and likewise by distilla|tion, and consequently is attenuating, resolving, penetrating, and deter|ging. After long Abstinence, it is ex|tremely acrid, and copious, it fer|ments with the juices of Vegetables, and consequently disposeth them to be chang'd into inflamable Spirits, it discovereth its Virtues in several Chirurgical uses. Besides, in the action of chewing, the Mucus (which is an Humour different from the Spittle, and by its Viscidity collects Air) mix|eth with the Aliment, and helps to

attenuate it. The necessity of Saliva or Spittle to dissolve the Aliment, ap|pears from the contrivance of Na|ture in making the salivary Ducts of Animals, which ruminate or chew the Cud, extremely open. Such Animals as swallow their Aliment without chewing, want salivary Glands; and Birds have them placed in their Maw. There are instances of Men who swallow'd their Meat whole, but Ruminated or chew'd the Cud after|wards. (Rumination is given to A|nimals to enable them at once to lay up a great store of Food and after|wards to chew it.) And Animals ru|minate more upon Hay than Grass, the Food being harder. From all which Observations it appears, that the Solution of the Aliment by Ma|stication is very necessary; and that without it the Aliment could not be duly disposed; for the other changes which it receives as it passeth through the Alimentary duct.

First, A great loss of Spittle causeth a decay of Appetite. This has been confirm'd by Experience in several, who have made it their constant cu|stom to chew Mastick; chewing and smoaking of Tobacco is only good in phlegmatick People.

Secondly, The humour of Saliva|tion is not properly Spittle, but pu|trified Blood.

Thirdly, The depravation of the Instruments of Mastication, by a paralytical disposition, or by the want of Teeth, as in old Men and Infants, is a natural Indication of a liquid Dyet, as of Milk and Broaths, and even such of them as take Solids ought to chew in order to make an expression of the Spittle.

PROP. II.

The Change which is made of the Aliment in the Stomach, is effected by Attrition of the solid Parts, or inward Coat of the Stomach, and

the action of a dissolvent Liquor assisted with Heat.

The Liquor in the Stomach con|sists of that which is separated from its inward Coat; of the Spittle, which is almost continually swal|low'd, and the Liquor which distills from the Gullet. By the help of this Liquor, and the constant Attrition of the solid Parts, the Aliment is dissolv'd by an Operation resembling that of making an Emulsion, in which Operation the Oyly parts of Nutts and Seeds being gently ground in a Marble Mortar, and gradually mix'd with some watery Liquor, are dissolv'd into a sweet, thick, turbid milky Liquor, resembling the Chyle in an Animal Body. That the Sto|mach in Animals levigates the Sub|stances, which it receives, is evident from the Dissection of some Animals which have swallow'd Metals, which have been found polish'd on the side next the Stomach. Birds being

without Teeth to make the first preparation of their Aliment, have strong and nervous Stomachs, to make this Attrition the stronger; and this motion in them hath been both seen and heard. The Rugae or Plyes of the inward Coat of the Stomach contribute to the detain|ing the Aliment in the Stomach. The Heat in Land Animals helps likewise to the Solution of the Ali|ment, but not much, for Fishes have a strong digestion without it, tho' by the tryal of the Thermo|scope, they have more heat than the Element which they swim in. It has been show'd before that the Spittle is a great Dissolvent, and there is a great quantity of it in the Stomach, being swallow'd constantly, at least in Sleep. He who eats a Pound of Bread swallows at least as much Spit|tle as Bread. This Liquor of the Stomach in a sound state is not Acid, for it has been found by Experiments,

that Pearls have pass'd through Cocks and Hens undissolv'd.

1. The Liquor of the Stomach, which with fasting grows extremely Acrid, and the quick sensation of the inward villous Coat of the Stomach, seem to be the cause of the Sense of Hunger.

2. Such as have, by the use of spirituous Liquors, weaken'd and de|stroy'd some of the solid parts of the Stomach, cannot recover a right Digestion, for this inward villous Coat when destroy'd cannot be restor'd.

3. This Liquor of the Stomach may (by reason of some saline Acri|mony) be made of some determined quality, and affect human Creatures with Appetites of other Animals, which in that case they can take without hurt; or it may likewise occasion an exorbitant Appetite of usual things, which they will take in such quantities till they vomit it up like Dogs, from whence it is call'd

Canine; in the first case the Organs of Taste are vitiated; both Diseases are cur'd by Dyet, opposite to this Acrimony, whether Alkaline, Acid or Muriatick.

4. Thirst and Hunger denote the state of the Spittle, and Liquor of the Stomach. Thirst is the sign of an Acrimony commonly Alkales|cent or Muriatick.

5. A Paralytical disposition of the Nerves of the Stomach, a deprav'd condition of the Liquor of the Sto|mach, something viscous, fat and oyly remaining there, destroys the Sensation of Hunger.

6. The Action of the Stomach is totally stop'd by too great Repleti|on, in which case both the Orifices of the Stomach by a necessary Me|chanism close, and neither will ad|mit nor expel any thing. In which case relaxing, as by warm Water, is the only proper Expedient.

The Signs of the Functions of the Stomach being deprav'd, are Pains in the Stomach many Hours after Repast; Eructations either with the Taste of the Aliment Acid, Nido|rose, or Foetid, resembling the Taste of rotten Eggs; Inflations, or the Sen|sation of Fulness; Sickness, Hickup, Vomiting, a Flushing in the Coun|tenance, Foulness of the Tongue. In general, whatever be the State of the Tongue, the same is that of the in|ward Coat of the Stomach. When the Taste of the Mouth is bitter, it is a Sign of a Redundance of a bi|lious Alkali, and demands a quite different Dyet from the case of Aci|dity or Sowerness.

PROP. III.

By Digestion in the Alimentary Duct the specifick Difference of all Substances is abolish'd, and the whole Action resembles Putrefaction.

Digestion is a Fermentation be|gun, because there is all the Requi|sites of such a Fermentation, Heat, Air and Motion, but it is not a compleat Fermentation, because that requires a greater Time than the Con|tinuance of the Aliment in the Sto|mach. Vegetable Putrefaction resem|bles very much Animal Digestion. Vegetable Putrefaction is produced by throwing Green succulent Vege|tables in a Heap in open warm Air, and pressing them together, by which all Vegetables acquire, First, A Heat equal to that of a Human Body. Secondly, A putrid stercoraceous Taste and Odour, in Taste resembling pu|trid Flesh, and in Smell Human Foe|ces. This putrid Matter being di|still'd, affords, First, A Water im|pregnated with an urinous Spirit, like that obtainable from Animal Substances, which Water is seperable into Elementary Water, and a vola|tile Animal Salt. Secondly, A vola|tile

oyly Alkaline Salt. Thirdly, A volatile thick Oyl. Fourthly, The remainder being calcin'd affords no fixt Salt; in short, every thing hap|pens as if the Subject had not been Vegetable, but Animal. Putrefaction utterly destroys the specifick Diffe|rence of one Vegetable from ano|ther, converting them into a pulpy Substance of an Animal Nature: Making the same Alteration very near as if the Vegetable had gone through the Body of a sound Ani|mal, for tho' such an Animal should entirely live upon Acids, no Part of its Body affords any acid fix'd Salt. * 1.1 This is so far true, that even the Herbs taken out of the Omasus of ruminating Animals afford the same Contents as putrefied Vegetables. But tho' this Action of Putrefaction comes the nearest to Animal Digestion, it so far differs from it, that the Salts

and Oyls are only detain'd in the Animal Body so long as they remain benign and friendly to it; but as soon as they putrefy entirely, are ei|ther thrown off, or must produce mortal Distempers.

PROP. IV.

The Gall is the principal Dissol|vent of the Aliment, and when it is peccant or deficient, there can be no right Digestion.

The Bile is of two Sorts, the Cy|stick or that contain'd in the Gall|Bladder, which is a sort of Repository for the Gall, and the Hepatick or what flows immediately from the Liver. The Cystick Gall is thick and intensly bit|ter, so that one Drop of it will make a whole Pint of Water bitter. The He|patick Gall is more fluid and not so bitter. There is no other bitter Hu|mour in a Human Body, besides Gall, except the Wax of the Ear.

The Gall is not a perfect Alkali, for it does not ferment with an Acid, but it is Alkalescent, entirely oppo|site to Acescents, and soon corrupti|ble, and convertible into a Corrosive Alkali. It is a saponaceous Sub|stance, being compos'd of an Alka|line Salt, Oyl and Water, all which can be extracted from it. The Bile, like Soap, takes out Spots from Wool or Silk, and the Painters use it to mix their Colours; by this sapona|ceous Quality, it mixeth the oyly and watery Parts of the Aliment to|gether. But tho' the Bile be an Oyl, it is not combustible till dry. These Qualities make it a most powerful and proper Dissolvent, which ap|pears by Experience. The Milk in the Stomach of Calves, which is co|agulated by the Runnet, is again dis|solv'd, and rendered fluid by the Gall in the Duodenum. Voracious Ani|mals, and such as do not chew, have a great Quantity of Gall, and some

of them have the Biliary Duct in|serted into the Pylorus. It is like|wise the chief Instrument (by its Ir|ritation) of the peristaltick Motion of the Guts. Such as have the Bile peccant or deficient are reliev'd by Bitters, which are a sort of subsidia|ry Gall. The learned Boorhaave has found the Gall of an Eel, which is most intensely bitter, a most effectual Remedy in such Cases. The com|mon Symptoms of the Excretion of the Bile being vitiated, are a yel|lowish Colour of the Skin, white hard Foeces, a Loss of Appetite, a lixivial Urine.

PROP. V.

The Bile is so acrid, that of itself it could not be admitted into the Lacteal Vessels. Therefore Nature has furnish'd another Humour, viz. the pancreatick Juice to temper its Bitterness and Acrimony, after it has done its Office.

The Pancreas is a large salivary Gland separating about a Pound of an Humour like Spittle, in twelve Hours. The Bile mix'd with Spit|tle loseth its Bitterness in time, and even Wormwood eat with Bread will do so, because it is mix'd with a great quantity of Spittle. The pan|creatick Juice likewise mixeth the Parts of the Aliment rendring the Chyle Homogeneous. When the Bile is not separated in the Liver the Foe|ces are white, but this is not occa|sion'd by the Mixture of the pan|creatick Juice.

PROP. VI.

Acrimony and Tenacity are the two Qualities in what we take in|wardly most to be avoided.

The papillous inward Coat of the Intestines is extremely sensible, and when the Acrimony is so great as to affect the solid Parts, the Sensation of

Pain is intolerable. The peristaltick Motion of the Guts, and the conti|nual Expression of the Fluids, will not suffer the least Matter to be ap|ply'd to one Point the least instant of Time; for the smallest quantity of Turpentine or Pitch will stick to the Fingers, but not to the Guts. But this Motion in some Human Creatures may be weak in respect to the Viscidity of what is taken so as not to be able to propell it, the consequence of which is dangerous, and perhaps fatal to the Life of the Creature. Substances hard, cannot be dissolv'd, but they will pass; but such whose Tenacity exceeds the Powers of Digestion will neither pass nor be converted into Aliment. Be|sides, the Mouths of the Lacteals may permit Aliment too acrimoni|ous, or not sufficiently attenuated, to enter in People of Lax Constitutions, whereas their Sphincters will shut a|gainst them in such as have strong

Fibres. The Mouths of the Lacteals may be shut up by a viscid Mucus, in which case the Chyle passeth by Stool, and the Person falleth into an Atrophy.

1. Fat or Oyl is necessary, as for Animal Motion, so likewise for this peristaltick Motion, of the Intestines, and lean People often suffer for want of it, as fat People may by Obstru|ction of the Vessels. The Omentum will melt by strong Motion, as has been found in Horses by hard run|ning.

2. This peristaltick Motion, or re|peated Changes of Contraction and Dilatation, is not the Lower Guts, else one would have a continual need|ing to go to stool. Wind and Di|stention of the Bowels are Signs of a bad Digestion in the Intestines, (for in dead Animals when there is no Digestion at all, the Distention is in the greatest Extremity) and Diarhaeas which proceed from Acrimony, La|xity

of the Bowels or Obstruction of the Lacteals.

PROP. VII.

The Mechanism of Nature in con|verting our Aliment; into Animal Substances consists chiefly in two Things. First, By mixing constant|ly with it Animal, Juices already pre|par'd. Secondly, By the Action of the solid Parts as it were churning them together. This is evident, if we consider first the vast quantity of Saliva mix'd with the Aliment in chewing. He that eats a Pound of Bread mixeth it very near with as much Spittle, and this separated from Glands that weigh only about four Ounces. Afterwards, the same Ali|ment is mix'd with the Liquor of the Stomach, the Bile and pancrea|tick Juice, and if we compute the quantity of Bile and Pancreatick, from the Weight of these Viscera in

respect of the salivary Glands, we shall find still a vastly greater quantity of these Animal Juices mix'd with the Aliment; this is not all, for when the Chyle passeth through the Me|sentery, it is mix'd with the Lymph (which is the most spirituous and e|laborated Part of the Blood) from the Glands of the Mesentery: So that the Juices of an Animal Body are as it were* 1.2 cohobated, being excreted and admitted again into the Blood with the fresh Aliment; all the while the solid Parts act upon the Mixture of Aliment and Animal Juices so as to make the Mixture more perfect; besides, none of these Juices, except the Liquor of the Inte|stines, are mix'd with the Foeces of an Animal, which in a sound State are hard. So that one may com|pute that a Pound of Bread before it enters the Blood, is mix'd perhaps

with four times the quantity of Ani|mal Juices. The same Oeconomy is observ'd in the Circulation of the Chyle with the Blood, by mixing it intimately with the Parts of the Fluid to which it is to be assimilated.

1. From whence it follows, that an Animal whose Juices are unsound or solid Parts weak can never be duly nourish'd, for unsound Juices can never duly repair the Fluids and Solids of an Animal Body, and without a due Action of the solid Parts, they never can be well mix'd. The Stomach, the Intestines, the Muscles of the lower Belly, all act upon the Ali|ment; besides, the Chyle is not suck'd but squeez'd into the Mouths of the Lacteals by the Action of the Fibres of the Guts: The Mouths of the Lacteals are open'd by the intestinal Tube, affecting a streight instead of a spiral Cylinder. Thus it is plain, that the Chyle must be peccant in Quantity or Quality when these Acti|ons

and Organs are too weak, and whatever strengthens the solid Parts must help the Digestion.

2. Diarhaeas and strong Purgati|ons must spoil the first Digestion, because of the great Quantities of Animal Liquids which they expel out of the Body; a vast Quantity and Variety of Animal Liquors are car|ried off by Purging, Air, Spittle, Mucus, all the Liquors that are sepa|rated in the Glands of the Alimenta|ry Duct, both Sorts of Bile, the pan|creatick Juice, Lymph, and sometimes Blood; computing the Quantity of these Secretions, makes it plain that the whole Juices may be carried off by purging, and when those Liquors are expell'd out of the Body, which by their Mixture convert the Ali|ment into an Animal Liquid, this cannot so well be perform'd.

3. The peristaltick Motion of the Intestines is the last that ceaseth in an Animal Body, for it remains af|ter

the Motion of the Heart is ceas'd. By the Entry of the Chyle and Air into the Blood, by the Lacteals, the Animal may again revive.

The Obstruction of the Glands of the Mesentery, is a great Impediment to Nutrition, for the Lymph in those Glands is a necessary Constituent of the Aliment before it mixeth with the Blood, and for the same Reason young Animals are most and best nourish'd, for the mesenterick Glands are largest in the Vigour of Youth; in old Age they vanish, and are ly|able to Obstructions. Therefore scrophulous Persons can never be duely nourish'd, for such as have Tu|mors in the Parotids often have them in the Pancreas and Mesentery.

4. In tabid Persons Milk is the best Restorative, for it is Chyle al|ready prepar'd; if a Nurse after be|ing suck'd dry eats Broath, the In|fant will suck the Broath almost un|alter'd.

5. The Chyle by Reason of the Smoothness of its Particles is white, it grows more grey in the thoracick Duct where it still retains the Fla|vour of the Aliment.

6. Animals which take a large quantity of Aliment by the Mouth may be less nourish'd, than those that take a smaller, for according to the Force of the* 1.3 chylopooetick Or|gans, a larger or less quantity of Chyle may be extracted from the same quantity of Food.

Astriction of the Belly is com|monly a Sign of strong chylopooe|tick Organs.

PROP. VIII.

The most subtile Part of the Chyle passeth immediately into the Blood by the absorbent Vessels of the Guts, which discharge themselves into the

meseraick Veins; their Largeness and Number demonstrate this, for they are numerous and vastly larger than their correspondent Arteries; besides, wherever there are Emissaries, there are absorbent Vessels, ex. gr. in the Skin, by the absorbent Vessels of which Mercury will pass into the Blood.

Birds which have strong and large Breasts, small Bellies, and their Ribs upon their Backs have no Lacteals nor thoracick Duct, and their Ali|ment passeth immediately into the meseraick Veins. If one considers the Capacity of the Thoracick Duct, and the Slowness of the Passage of the Aliment by the Lacteals through it, and at the same time the great quantity of some Liquors, as of cha|lybeat Water, which in some pass in a small Time by Urine; by an easy Calculation he will be able to de|monstrate that such a Quantity could not pass into the Blood by the Tho|racick Duct in so short a time.

Therefore when the Intention is to give an immediate Refreshment to the Spirits, as after great Abstinence and Fatigue, Thin or liquid Aliment is the properest, and for the same Reason Chalybeat Waters seem to be a proper Remedy in Hypochon|drical cases; their subtle and divided Particles are taken immediately into the Miseraick Vessels, and carried streight into the Liver and Spleen.

Notes

• * 1.1

  Vide Philosophical Transactions.
• * 1.2

  i. e. new distill'd
• * 1.3

  Which make the Chyle.