On Digestion of Food

ON DIGESTION

CHAPTER IV.

ON DIGESTION.

THE most recent systematic teacher of physiology defines diges-
tion as " the process by which food is reduced to a form in which
it can be absorbed by the intestines and taken up by the blood-
vi-sels." 1 The process consists in the aliments being passed along
a canal, thence called the " alimentary canal," running through
the body, where it comes in contact with fluids oozing out from
various glands, which mixing with it dissolve it, and reduce it to
a homogeneous juice or "chyme."

The more perfectly and quickly this end is attained, the more
healthy is the digestion.

These fluids resemble one another in being watery, saline, and
albuminous, like the serum of the blood, so that they are well
adapted for passing readily through the mucous membranes by
endosmose. They pass in, as they passed out, freely, and carry
in with them the nutriment prepared in the alimentary canal.
But there the resemblance ceases; and the differences of the fluids
poured from the different glands are very marked, and their ac-
tions on the various constituents of the diet are strikingly special-
ized .

1. The saliva, secreted from the glands of the mouth, is alka-
line, glairy, and adhesive, and possesses the power of converting
very rapidly the unabsorbable starch into soluble and absorbable
sugar.

2. The gastric juice, secreted in the thin layer of gland which
lines the cavity of the stomach, is acid, and can dissolve, so long
as it is acid, the solid albumen and fibrin of flesh food.

1 Dalton's Human Phyisology, fifth edit. chap, vi., whore will be found
a complete rSxumi of the scattered contributions of others up to the present
time, often illustrated and criticized by the light of the author's original in-
vestigations on this subject. An old rfsumt of mine, entitled Digestion and
its Derangements (London, 1856), is out of date, as well as out of print.

102 GENERAL DIETETICS.

3. The pancreatic juice is again alkaline, 1 very full of albumi-
nous organic matter, and capable of exerting a peculiar influence
on fatty matters. It disintegrates them, and reduces them to a
state of emulsion, so that the mixture of fat in the watery fluid it
floats in, is white and opaque. In this creamy state, it is capable
of soaking through the mucous membrane and passing into the
blood, by the same way as the starch and fibrin.

4. The bile is very different from any of the above fluids in
chemical reaction and contents, and it does not appear to possess
the power of dissolving starch by turning it into sugar, or of dis-
solving fibrin, or of emulsioning fat in any degree equal to pan-
creatic juice, though it is itself of a soapy nature, as is shown by
the commercial use of ox-bile by carpet cleaners to remove grease-
spots. It is neither acid nor alkaline,. but it possesses considera-
ble bleaching powers, and, also, arrests decomposition in animal
substances. In this latter capacity, it is highly conducive to our
comfort by obviating that intolerable odor which distinguishes the
excretions of patients in whom the bile is deficient. But, with
all this, it does not clearly appear how any of its known physical
properties can aid in the constructive assimilation of nutriment.
Yet aid it does, most decidedly. If, in consequence of accident
or disease, the flow of bile into the alimentary canal is wholly cut
off, the animal rapidly emaciates, and dies starved. Even when
the supply of bile is only partially diminished, as in the instance
of some of our patients, there is a marked deficiency of nutrition,
shown in loss of weight and anaemia. Now, this would not hap-
pen if bile were a mere excrementitious fluid containing ingredi-
ents resulting from the disintegration of the tissues, and designed
merely for their removal from the body. It has assimilative
functions to perform beyond the simple drainage of the blood,
though what those functions are can be expressed only in the
vaguest terms at present, and the most prudent and most recent
physiologists decline to give a definite opinion on the uses of the
bile.

5. The intestinal juice is secreted alkaline, and possesses the
power, like the saliva, of converting starch into sugar; but, unlike

1 Dr. Dobell questions its alkalinity. Perhaps it varies with the state of the
body.

ON DIGESTION. 103

that fluid, does not lose its power in presence of an acid. It, also,
has a certain solvent power over albumen, inferior, indeed, to that
of the stomach, but stronger in this respect, that it is not checked
by the bile or pancreatic juice.

Thus, we see that a meal, as it passes downwards, is irrigated
first by a watery fluid which, as it dilutes and adds to its bulk,
dissolves or fits for absorption a great portion of its starchy con-
stituents. Then, it is further irrigated by a still more dilute fluid,
which dissolves its meaty part. Then, the fat is washed out of it
by the stream of pancreatic juice. And, simultaneously, the bile
is poured on it in a continuous stream, which makes it, in some
unexplained way, more easy to be taken up as nutriment. After-
wards, the intestinal juice, oozing out in small quantities through-
out a long canal, seems fitted to make up the deficiencies of any of
the previous solvent acts.

The daily quantities of these fluids, as estimated, mainly, from
the results of Drs. Bidder and Schmidt's experiments, may be
reckoned, at least, to equal the following :

Of saliva, ......... 3| pints,

Of gastric juice, 12 pint-,

Ot bile, 3} pints,

Of pancreatic juice, ....... 1 pints,

Of intestinal juice, ....... pint,

making in all nearly three gallons. Of this, ninety-six per cent,
is water, of which only so much passes away in the stools as pre-
vents them from being inconveniently solid. The rest, therefore,
that is to say two gallons and a half, is restored to the blood by
absorption.

" The clearest notion we can gain of the business performed by
all this two dozen pints of water which exude on the nuii-ons
membrane of the intestinal canal, and are by the same membrane
taken up again, is by viewing them as a circulation. It is con-
stantly going its rounds like an endless chain, finding and taking
up inside the solid structure of the body substances which ought
to corne out and be got rid of, finding outside nutriment which
the body wants, and conveying it in.

"Truly, when a man contemplates with the eye of the reason
this unceasing journey, this great current so entirely 'removed from
the cognizance of our senses, he is at first confounded with the

104 GENERAL DIETETICS.

novelty of the ideas it excites (ingenti motu stupefactus aquarum)
and almost refuses to receive them. It is highly important, there-
fore, to bring it frequently before the mind till it becomes habitual,
for there is no view of living phenomena so practically weighty
for the medical man." 1

In addition to this, there is a quantity of fluid introduced as
beverage. Water passes straight through the mucous membranes
unchanged, and alcohol, with a change of no weighty importance;
and dissolved in them are numerous minor substances not strictly
dietetic, though valuable by acting pleasurably or medicinally on
the nervous system.

Rightly, then, has digestion been likened by an old chemist to
a process of " rinsing ;" 2 all that is required is washed out of the
alimentary substances, and the remains passed on to be got rid of
along with the waste products of chemical life.

Of the reason why these various secretions are able to digest the
various constituents of our food, we know absolutely nothing. We
find an albuminous matter in saliva, and we call it " ptyalin ;" we
find an albuminous matter in gastric juice, and we call it "pepsin;"
we find an albuminous matter in the pancreatic juice and we call
it " panereatin ;" but the only distinguishing point about each is
that it acts upon starch, or acts upon flesh-meat, or acts upon fat,
just as the fluid from whence it was concentrated acts. Ultimate
chemical analysis merely shows their resemblances, and not their
differences. The nearest approach to a similar proceeding in
nature is the operation of malting, where, aided by heat and mois-
ture, starch is turned into sugar by the presence of "diastase;"
and it is remarkable enough that when albumen is artificially dis-
solved by gastric juice in the laboratory, a peculiar odor some-
what like that of malting is given off. But here our information
ceases; there are no more points in diastase, to distinguish it
chemically from ordinary albumen, than there are in pepsin or
panereatin.

In bringing to bear upon dietetics the observations of physiolo-
gists, the main things the physician has to consider are the mechan-
ical condition in which the food should be brought, the influence

1 Digestion and its Derangements, p. 31.

2 Letheby On Food, p. 48.

ON DIGESTION. 105

of its several solvents, and the times when they are ready to re-
ceive it.

Chewing is the first provision made for securing a due mechan-
ical condition. The perfection consists in so breaking up the
mouthful that it should be as completely as possible permeated by
the saliva. The object of this is, in the case of meat, to soften it
in preparation for swallowing and for future solution in the stom-
ach ; in the case of starchy matter, to convert it into "glucose"
or sugar.

"With regard to the amount of chewing required by flesh food,
there is a good deal of popular misconception. Persons with bad,
false, or tender teeth are often found to fancy that a vegetable diet
is more suited to their imperfect power of mastication than an ani-
mal one ; and we not unfrequently see mothers instructing their
children carefully to chew meat, and neglecting the same precau-
tion in respect of vegetables. Physiology teaches an opposite
caution. It is desirable, indeed, that the jaws should break up
muscular fibre, lest it should perchance stick in the gullet, and be
certainly difficult of penetration by the gastric juice in the stom-
ach ; but to a vegetable aliment the performance is owing of more
important functions. It is still more indispensable that it should
be broken up, for it has to be immediately acted upon ; and it is
indispensable also that it should be detained in the mouth till
enough saliva to convert its starch into glucose has been secreted.
Complete mastication, therefore, important for both, is still more
important for vegetable than for animal food ; and the leisurely
performance of the operation cannot be prudently omitted by a
mixed eater.

It may serve to remind us of this, to reflect that while lions
and tigers and wild dogs bolt their food, cows not only spend the
greater part of the day over their nibbled meals, but give it a
second chewing when in repose.

Doubts have been thrown (Dalton's Human Physiology, page
116) upon the importance of the action in the mouth to the con-
version of starch into sugar; but the following easy experiment
seems sufficiently convincing. Take some boiled starch, say in
the shape of arrowroot, and heat it with potassio-tartrate of copper.
There is no change in the blue color of the salt. Now, put some
in the mouth, and hold it a few moments only. When it is again

106 GENERAL DIETETICS.

heated with potassio-tartrate of copper, the metal is precipitated,
and shows by its brilliant yellow color an abundant quantity of
sugar.

The saliva r then, begins to convert starch into sugar immedi-
ately ; and it is not slow to extend its operation to the whole mass
submitted to it. A protraction of the foregoing experiment will
show this. A mouthful of boiled arrowroot held in a healthy
mouth for five minutes, will show r afterwards scarce a trace of
starch remaining.

But it is true that the morsel is hardly ever allowed to remain
in the mouth long enough for its complete conversion ; hardly
ever is it sufficiently boiled and chewed for the saliva to affect the
whole of it. Much free starch and free saliva must be carried
down the resophagus. During its passage the action goes on, and,
doubtless, as much saccharine transformation takes place in the
latter as in the former locality. But in a minute or two it must
arrive at the stomach, and there the acidity of the viscus is said
to put a stop to the saccharization. On this arrest of the salivary
action by the presence of acid,. Dr. Dalton's opinion of its slight
Influence in digestive solution is grounded. Nevertheless, once
that the mass has passed through the pylorus, its acidity is neu-
tralized, the action of the remaining saliva recommences on the
starch yet unconverted, and this action is reinforced by the intes-
tinal juice.

By the unconverted starch, I mean not only that which was
unchanged on arriving at the stomach, but also a good deal set
free since that stage of digestion. For, besides the saliva, there
practically comes into play in the solution of starch that which I
have described as temporarily arresting it, to wit, the gastric juice.
Cookery, even when most efficient, rarely ruptures the whole of
the granules. Many escape in the best, and in bad cookery the
majority escape. They cannot, therefore, be affected by the saliva,
till their albuminous envelope has been dissolved by the gastric
juice. Then, the amylaceous matter may be converted into sugar,
either, rapidly, by the saliva present, or, more slowly, by the
pancreatic and other intestinal secretions.

For the reduction of starch, therefore, so as to bring vegetable
food into a condition capable of easy digestion, the first point is
that the salivary glands should secrete a sufficiency of fluid; and

ON DIGESTION. 107

this not merely at the time of mastication, but that they should go
on supplying it as long as any starch remains unconverted. Then,
it appears extremely probable that the gastric glands aid the future
carrying on of the process, though the acidity of the stomach pre-
vent its continuance at the time of its prevalence.

Now, the salivary glands in the healthiest persons are liable to
derangement from purely external circumstances acting on the
nervous system. Temporary emotion affects them temporarily,
and chronic emotions affects them chronically. We all are famil-
iar with the dry lips of the coward, the lover, the pitiful, and how
the tongue cleaves to thereof of the mouth when pain is endured,
or when bad news is brought. "Bread eaten in sorrow" can
hardly be swallowed, so long it takes to moisten the morsel.
Again, bodily exertion parches the throat. It cannot be expected
that meals of mixed food, swallowed when the body is under the
influence of the circumstances quoted in illustration, should be
dissolved, or nourish the tissues as they ought, And there is
nothing surprising in the fermentation of the undigested vegeta-
bles, and the formation of flatulence by the carbonic acid which
results.

Under the same circumstances, a portion of the solid meat re-
mains undissolved, and is often thrown away unaltered by vom-
iting or diarrhoea; for the stomach is influenced contemporane-
ously with the mouth, as is clearly shown by the proverbial loss
of appetite from mental causes.

It is in this arrest of secretion that the sedative action of alcohol
comes in useful. It is an anaesthetic, and prevents the effect of the
nervous system upon the alimentary canal from being so deleteri-
ous as it has been shown naturally to be. A few teaspoonfuls of
good strong wine or dilute spirit will often restore the lost power of
taking food, and is an instinctive indulgence, as a protective against
the sundry blows inflicted on digestion by the exciting nature of
social life in the present regimen of the world. It is possible to
imagine a state of society, as among the Pitcairn islanders, for ex-
ample, where everybody was apparently the better for taking no
alcohol in any form, but even in that instance, the abstinence does
not seem to have lengthened life, and it is certain that in Europe,
it would shorten it for many of our most active and useful citizens.

Equally important is the absorption of the sugar thus formed

108 GENERAL DIETETICS.

from the starch. In health, a very great part is absorbed in the
mouth and gullet, sometimes all, for chemists have great difficulty
in finding it in the stomach, unless it is swallowed in excess.
Some of it is probably converted into the lactic acid, which aids
the solution of flesh food, and the rest taken up as sugar by the
intestines. Still, even in health, a good deal of both starch and
sugar escape, and appear in the faeces. But, in the catarrhal state,
the mucus which lines the membrane is an almost impermeable
impediment to osmosis, from its insolubility in water, and arrests
absorption in proportion to its quantity. All mucus is a degree
of disease and every Briton knows how easily it is formed by
very slight external influences.

It is clear, then, that for the easy digestion of starch the w r hole
of the alimentary canal must be in a normal condition, and the
nervous system not exhausted by recent excessive use.

The Mechanics of Digestion refer to the provision which is made
for the food being duly brought into the sphere of action of the
solvents described above. First comes Chewing, the importance
of which, as a means of saturating the mass with saliva, has been
already insisted upon. Here may be mentioned, further, the im-
portance of its completeness, for the sake of reducing muscular
fibre to a fine pulp, so that it may be quickly infiltrated by the
gastric juice on its arrival in the stomach.

"In the human subject, the teeth combine the characters of the
carnivora and the herbivora. The incisors, four in number in
each jaw, have, as in other instances, a cutting edge running from
side to side. The canines, which are situated immediately behind
the former, are much less prominent and pointed than in the car-
nivora, and differ less in form from the incisors on the one hand,
and the first molars on the other. The molars again are thick
and strong, and have comparatively flat surfaces, like those of the
herbivora; but, instead of presenting curvilinear ridges, are
covered with more or less conical eminences, like those of the car-
nivora. In the human subject, therefore, the teeth are evidently
adapted for a mixed diet, consisting of both animal and vegetable
food. Mastication is here as perfect as it is in the herbivora,
though less prolonged and laborious ; for the vegetable substances
used by man, as already remarked, are previously separated, to a
great extent, from their impurities, and softened by cooking, so

ON DIGESTION. 109

that they do not require for their mastication so extensive and
powerful a triturating apparatus. Finally, animal substances are
more completely masticated in the human subject than they are in
the carnivora, and their digestion is accordingly completed with
greater rapidity." !

However much natural selection may have rendered stronger
the surviving species of other animals, it has, in the case of the
human teeth, proved injurious to the perfection of our race.
Artists have, unhappily, taught us to see loveliness in button
mouths, bud-like lips, round dimpled chins, tiny pearly teeth, and
to recognize aristocracy in hatchet faces. You take up a skull in
one of the bone-houses near old fields of battle (say at Hythe,
where Pict and Briton, and others besides, grin so grimly at us),
and you cannot enough admire the evenness, the firmness, the
completeness of the set of half-worn, yet quite sound teeth ; but
you are fain to confess that to have a wife, or a son, or a daughter
with a prominent square jowl like that, would be a severe trial to
your aesthetic feelings. You are incurably perverted by the me-
diaeval association of moral purity and intellectual refinement with
pitifully weak jawbones ; and a big-mouthed broad-nosed Helen
would never have been the mother of your children yet would
she have saved you many a dentist's fee. Narrow jaws can hold
but few teeth ; if the natural numbers come, some must be ex-
tracted, or else they crowd^ together, and decay from pressure;
and there is no feature which is so markedly hereditary as narrow
jaws ; as the mother is, so is the offspring.

When, by the grinding machinery above described, the food has
been reduced to a pulp, it is easily embraced by the tubular mus-
cles of the pharynx and oesophagus, and passed by their steady,
wavelike motion downwards to the stomach ; the passage is
opened before it, and its return is prevented by the closing of the
tube behind as it goes onwards. The sensibility of the cesophagus
is so very slight, that we do not, in ordinary circumstances, feel
the morsel going down; but if it is peculiar in shape and nature,
we become aware how slowly and steadily it proceeds, and ought
to proceed. For during this passage, much of the sugar and solu-
ble salts, and the watery part, is taken up by absorption, and if

1 Dalton's Physiology, chap, vi, p. 109.

110 GENERAL DIETETICS.

it is hurried by bolting mouthful after mouthful in rapid succession,
scant justice is done to the victuals, and a risk of indigestion is
incurred. The healthy circulation of saliva in this round is very
great ; we have seen lately how many pints are poured out daily
in the mouth, and of this but little finds its way to the intestines,
the rest being taken up in the resophagus and stomach, principally
in the former. So, the importance of not interfering with its due
action can be easily understood.

Once in the stomach, the mass of food acquires a rotation from
the wavelike movement kept up by the peristaltic muscles of the
stomach. Their alternate contractions and relaxations press on
the mass, much as the undulations of a serpent carry it over the
ground only in the latter case the undulating body is free, in the
former it is fixed. The surface, being the part subjected to the
moving power, moves quicker than the centre, and thus the whole
contents of the stomach are rotated as a uniform mass, from left
to right, and continually irrigated by the gastric juice along the
depending, lower, and larger part of the sac. As it passes the
opening of the pylorus at the other end, the narrowing of the sac
squeezes out, with a somewhat quicker motion, such portion as is
dissolved into creamy chyme, and it oozes on into the duodenum,
leaving the still undissolved substances to flow along the shorter
and upper curve of the stomach back to the starting-point. Thus,
a slow, rotatory movement of the whole mass is sustained till all
is dissolved, or, at least, so far reduced in size as to get through
the pylorus.

The rotation seems to be continued in the intestines, if one may
judge fairly of the action of their peristaltic fibres by the move-
ments seen, immediately after death, in the intestines of a vigor-
ous animal slaughtered for food. And the biliary ducts appear,
also, to have a peristaltic action, rolling out gradually and regu-
lating the flow of bile into the duodenum. Now, over all these
involuntary and unfelt but constant wavelike movements, the
nervous system presides ; and they are, without doubt, seriously
affected by all that affects the nervous system, notably by mental
emotion and bodily exhaustion. The oesophagus is sometimes so
paralyzed by a sudden shock during a meal, that it does not close
behind the victuals swallowed, and they are thrown up by a sort
of regurgitation. Even some hours after a meal, the arrest of the

ON DIGESTION. Ill

stomach's action by emotion may cause vomiting. And many
instances arc on record of a mental emotion so arresting the biliary
ducts as to produce jaundice. The late Dr. Macleod, of St.
George's Hospital, used to relate a scene which he saw in his own
practice : a young lady with distended abdomen was charged with
being privately married, and her eyes and skin had got bright
yellow before he left the room. And, in the wild times, when
people really did get into a passion sometimes, they are stated by
bystanders to have often become jaundiced. Few of ns have ever
seen an adult in a rage of the old sort, so that we must not ques-
tion the accuracy of the statement.

Yriicther absorption of the dissolved alimentary substances is
affected by similar causes is not clear. I see no reason to suppose
that it is, as endosmosis is such a purely physical act, that the
nervous system can control it only very indirectly. But, as the
supply is cut off, it cannot, of course, be active during the preva-
lence of such interferences.

The subject of the impediments to digestion arising out of dis-
ease of various kinds, is of too great weight to be cited merely as
an illustration, and will be considered more fitly in a future part
of the volume. Here is the place for a few reflections on the
suitability of different articles of food.

Aliments may be called digestible when they yield readily all
their nutritious particles to the fluids destined for their reduction
to chyme. It is clear from what has gone before, that a compara-
tive estimate of their digestibility cannot be made merely by
reckoning, as Dr. Beaumont did, the duration of their sojourn in
the stomach. That well-known physician is familiar to all, from
having made a series of observations on a Canadian voyageur who
had a permanent opening into his stomach, a healed gunshot
wound. This was easily looked into, and the time consumed be-
fore the victuals passed out noted. But the results, which are
often taken as an infallible guide by the dietician, are not truly in
accordance with what general experience teaches us on this matter.
For example, salt tripe or pig's trotters, by this theory, take only
one third of the time demanded by roast beef, the former dish
being dissolved in the stomach in one hour, and the latter requir-
ing three, while veal took four hours and a half. Sour-cnmt
seemed to be twice as digestible as soup made of beef and vegeta-

112 GENERAL DIETETICS.

bles. Mutton was three quarters of an hour longer in digesting
than beef, and so on. Green vegetables, again, are hardly at all
touched by the gastric juice are we therefore to conclude that
they are useless ? surely, the general observation that they are
very digestible by a healthy man is more in accordance with fact.

I do not lay much stress on the objection to these experiments
arising out of individual peculiarity of constitution ; for in fact
the subject of observation was a remarkably robust man, little
affected by external circumstances, and able to carry on, in spite
of the hole in his side, the laborious duty of conducting timber-
rafts down the American rapids.

In order to give observations like Dr. Beaumont's their full
value, they should be corrected by a set of similar tests conducted
upon the duodenum and ilia, for which a good opportunity has
not yet occurred. Experiments on animals have been made, it is
true; and they establish the fact that the intestinal juice is of
great importance, and that the pancreas, if not the liver, aids in
the solution of food j 1 but the alimentary canal, and the habitual
diet, of the lower creatures are so different from ours, that a com-
parison of the behavior of different articles of food in their case,
affords no practical experience for human dietetics.

Something in the way of a comparative estimate might be
made by laboratory experiments on the juices removed from the
body, separately and mixed. Pending advances in this direction,
the following general conclusions are, perhaps, all the rules our
knowledge enables us to lay down :

The degree of Cohesion has an important influence upon digesti-
bility. Tough articles, incapable of being ground up by the teeth,
remain unused by the alimentary organs, while fluids and semi-
fluids lead the van of digestibles. The tissues of young vegeta-
bles and young animals are, for this reason, more digestible than
those of old specimens of the same class. And emasculated
beasts, having 'softer muscles, are better suited for the table than
perfect males. It is desirable also that the post-mortem rigidity,
which lasts several days in some animals, should have merged in
softness before the meat is cooked. But this object, usually at-

1 See the plates illustrative of Dr. Dalton's experiments, Human Phys., p.
146.

ON DIGESTION. 113

tained by hanging in the larder, may be arrived at equally well
by immediate cooking, before the rigidity has set in. In warm
climates and exceptionally warm weather, the latter course is the
preferable of the two.

That culinary preparation is the most efficacious, which most
breaks up the natural cohesion of the viands. And it may be
observed that the force of cohesion acts in all directions ; and it is
of no use for a viand to be laterally friable, if it remains in lon-
gitudinal strings.

Fat interposed between the component parts of food diminishes its
digestibility. It is the interstitial layer of fat between the bundles
of fibres of beef that makes it less digestible than mutton, and
that causes larded meats often to disagree.

Dilation favors digestibility. Yet it may be carried too far.
Even water will sometimes run through the alimentary canal,
carrying on too rapidly the matters dissolved in it. And inert
substances, such as w r oody fibre, if mixed up in too great quan-
tity with food, dilute it so much that the central parts of the mass
do not come at the digestive mucous membrane. Gelatin, proba-
bly in the same way, retards the digestion of food if too concen-
trated.

Too high a temperature retards digestion. It is not merely that
the gastric, and presumably the other digestive solvents, are de-
composed by heat above that of the body, but the amount of se-
cretion and the muscular acts necessary to forward solution are
arrested by its local action. This applies principally to starchy
foods, which are often taken hotter than at all suits the salivary
glands. Meat has time to cool before it gets down to the labora-
tory prepared for it in the stomach.

The application of these rules to practice is not difficult; but it
is obviously impossible to compare articles of diet unless they are
of a definite quality; and, therefore, it will be understood that
all those spoken of are supposed to be of the very best sort, and
dressed in the way best adapted for securing their virtues.

Some years ago, I printed what I called a " Ladder of meat-
diet for invalids," 1 which I will repeat in a future part of this
volume, when we come to consider the regimen of the sick. I

1 The Indigestions, p. 101, 3d edit., Philadelphia, 1870.
8

114 GENERAL DIETETICS.

there conclude with roast joint of mutton, which is the "promised
land " of the convalescent ; so, that dish may fairly here begin
the list, which may form a sort of skeleton framework from its
actual or possible position in which may be judged roughly the
comparative time which each article is likely to require for its di-
gestion. When time and strength have to be economized, or
where a full quantity is required for purposes of nutrition, it is
wise to adhere to the leading names on the list. Where modera-
tion can be calculated upon, and full leisure secured, a healthy
man cannot be called imprudent for indulging his appetite for va-
riety by descending to the very bottom. Indeed, to do so, within
reasonable bounds, contributes to high health ; for it is certain
that an important element in making the most of food is variety.
It is not enough to supply in proper amount the proximate diet-
etic substance; both in our own race and in domestic animals
there is risk of a falling off in condition unless different substances
of the same class are employed in rotation. The very strongest,
perhaps, can bear uniformity without injury, but to the average
man or beast it is as finally noxious as it is distasteful. Dr.
Parkes suggests that the good effect of variety is probably on
primary digestion, improving the appetite and so causing more
food to be taken by counteracting the cloying result of sameness. 1
But I think it goes further than that, for few can fail to have no-
ticed in their own personal experience, if once the attention be
called to it, how often a most indigestible dish, when partaken of
as an occasional luxury, has seemed to sit easy on the stomach,
and to nourish well though its quantity has been spare. The
great art is to give it time and space, and to be moderate.

Dr. Parkes makes the further very practical suggestion, that
where variety of sort of food is unattainable, variety of cookery,
to a certain extent, fulfils the same object.

Table of Precedence in Digestibility of some Articles of Animal Food.

Sweet-bread, and lamb's trotters.

Boiled chicken.

Venison.

Lightly boiled eggs, new toasted cheese.

Roast fowl, turkey, partridge, and pheasant.

1 Parkes, Practical Hygiene, p. 186, 4th edit.

ON DIGESTION. 115

Lamb, wild duck.

Oysters, periwinkles.

Omelette (?), tripe (?).

Boiled sole, haddock, skate, trout, perch.

Tripe and chitterlings. 1

Koast beef.

Boiled beef.

Kump steak.

Roast veal.

Boiled veal, rabbit.

Salmon, mackerel, herring, pilchard, sprat.

Hard-boiled and fried eggs.

Wood pigeon, hare.

Tame pigeon, tame duck, goose.

Fried fish.

Roast and boiled pork.

Heart, liver, lights, milt, and kidneys of ox, swine, and sheep.

Lobsters, shrimps, prawns.

Smoked, dried, salt, and pickled fish.

Crab.

Ripe old cheese.

Caviare.

The comparative digestibility of various vegetable dishes is
easier to estimate than that of animal food ; it is in a direct ratio
to the facility with which they are reducible into a homogeneous
mass, by mechanical means, from their natural form. And they
are more readily digested if this reduction takes place through
chewing in the mouth, rather than by mashing in the kitchen, as
they in the first way become permeated more thoroughly by the
saliva. If, on the score of defective teeth or other reasons, a pref-
erence is given to artificially broken-up vegetables, they should be
retained in the mouth longer than is required by the mere prepa-
ration for swallowing.

The influence of the mind over digestion must not be forgotten.
" Bread eaten in sorrow " remains unabsorbed, and it is not with-
out reason that, even in the earliest times and among the most
barbarous tribes, companionship during meals has always been
sought. It is not only painful reflections which disturb the di-
gestion ; any concentrated thought is equally injurious, and inju-
rious in a close proportion to the intellectual powers of the indi-

1 The " tripe ' as made in America would seem from Dr. Beaumont's ac-
count to be more digestible than the rich dish we prepare from it here.

116 GENERAL DIETETICS.

vidual. The only people fit to feed alone are those fluttering
butterflies whose intellects do not dispose them to concentrate
their thoughts, and whose good luck exempts them from the need
of trying. And even these instinctively seek society. To the
brain-worker and the body-worker, cheerful distraction at meal-
times is a rule of imperious necessity, the habitual neglect of
which entails chronic disease and the early failure of vital powers
as a certain punishment.

The adjuncts of family meals should be studiously made as
agreeable as possible. A change of clothes, clean hands, and
courteous manners, should not be reserved for company, but en-
forced as a daily habit. If allowed to be omitted, it becomes a
labor instead of a matter of course. Table decking is an elegant
art, capable of exhibiting the good sense, as well as the good
taste, of the artist, and highly promotive of ease of mind in the
company, however small, or however familiar. If flowers are
lacking, there are always leaves to be had, and I have seen toad-
stools with mosses and lichens so arranged as to form a centre-
piece that Cellini must have praised. I do not see why we should
not have music and singing at domestic meals, as well as at city
feasts. All are not eating at once, and a change of performers
might be kept as long as required. The cook, also, should be
encouraged to make the dishes which are exposed to the eye as
pleasant to look at as possible, not so much by adornment, which
is apt to be vulgar, as by concealing all that is untidy and sugges-
tive of painful idea. The forms of animals, in fact anything
which makes us remember that the food has been a living animal
at all, should never be conspicuously displayed, but rather covered
with such vegetable garnish as is capable of harmonizing with the
character of the dish.

Ease of body, as well as of mind, is requisite for complete di-
gestion. Muscular exertion should be avoided immediately before
and immediately after all substantial meals. The repose previous
need not be long ; a nap of forty winks, dressing, and washing,
are usually enough to prepare even an exhausted pedestrian or
hard rider for a good dinner. The best test of due preparation is
a healthy appetite without any feeling of faintness or squeam.
The rest after meals requires rather more judgment and self-con-
trol. Instinct induces us to take it, but does not tell us to avoid

ON DIGESTION. 117

excess. Now, it is certain that to a healthy person excess is very
possible. Sleep, for example, after dinner retards digestion, and
allows the distended stomach to act injuriously on the circulation
of the brain. It is proper only for very aged persons or invalids.

I have heard it argued by persons more ready at observing the
facts of natural history than at reasoning upon them, or perhaps
still readier at finding an excuse for laziness, that dogs and other
carnivorous animals naturally betake themselves to sleep after a
repast. That is true, but, then, it must be remembered, that in
the wild state their chance of a meal comes but seldom; they must
take the food when they can get it, and to guard against starvation
overload their stomachs. The lethargy which follows is a neces-
sity, and there is no evidence that it prolongs their lives. Those
breeds of dogs which live most in the company of man, and feed
on the mixed and cooked diet of their masters, usually give up
the practice of sleeping after meals along with their gluttony, and
to all appearance seem to suffer less frequently from indigestion
than their cousins at the kennels, who require very careful treat-
ment to preserve their health.

The best employment after a hearty meal is frivolous conversa-
tion, accompanied by such gentle sauntering movements as are
encouraged by a well-ventilated drawing-room or garden. Then
is the time, also, for those true games where luck and skill are so
combined as to have the character of game and not of business.

I have ventured so far to go beyond what might seem the limit
of a dietician's tether, because it is upon these social considerations
that depends the determination of the best times of meals for
healthy persons. For the heaviest repasts, those hours should be
selected when we can secure to the fullest extent leisure of mind
and body, and the opportunity of applying the aids mentioned
above as tending to promote them. It is useless to prescribe the
times for meals, or even their number, unless with a regard to the
disposal of the remainder of the day, whether that is regulated
by choice or necessity.

The intervals between meals, also, depend on the occupations
which fill them up. Sleep retards digestion, and therefore a con-
siderably longer period may be allowed to elapse between the last
food at night and the first in the morning than is suitable during
the day. Violent exercise of mind or body also retards digestion,

118 GENERAL DIETETICS.

and therefore, when this is practiced, food is not called for so soon
as on a day of rest. I have often observed that, in spite of a
late breakfast, a keen appetite often comes on Sundays before one
o'clock to lawyers and merchants, who on working days do not
care to eat till two or three, nor even then. Whereas, busy
medical men whose work is more continuous, though less severe,
adopt the early Sunday dinner hour only with reluctance.

There can hardly be any exceptions to the rule, that after the
night's sleep, and the long fast which has emptied the digestive
organs, food should be taken before any of the material business
of the day is taken in hand. Work done before breakfast is more
tiring, and, with due deference to certain well-meaning enthusiasts
for early rising, is not done so well as after the stomach has been
fortified with what it must require, if in a healthy state. The
hour of rising must, therefore, regulate the hour of breakfast. It
is no proof of health or vigor to forego it without inconvenience,
nay rather the contrary ; but it is proof of health and vigor to be
able to lay in then a solid foundation for the day's labor. The
natural appetite for food should be fully and completely appeased ;
and if there is a desire for meat, there is no reason for declining
it ; indeed, where mental work has to be done, it had better not
be omitted. For mere bodily toil, a breakfast merely farinaceous,
such as porridge, bread, milk, and butter, is most adapted, to
which the usual additions de luxe may be made according to
choice.

Not more than five hours should elapse before food is again
taken. To some persons, from habitual neglect, the appetite does
not arrive so soon ; and then if they sit down to an unaccustomed
luncheon, they feel stupefied by it, and quote this experience as
an evidence that a midday meal is unwholesome for them. The
stomach requires a gradual education after it has got into bad
habits ; so, beginning with a biscuit and a little milk, the patient
should advance in quantity, till he arrives at the amount which
is shown to be the proper amount by his sitting down to his sub-
sequent dinner hungry and unexhausted. The proper amount
varies much in different persons and different circumstances, and
the only general description that can be applied to it is " moder-
ate."

Instead of a light intercalary meal, some families prefer to take

ON DIGESTION. 119

a substantial high dinner in the middle of the day. This seems
to suit idle people and children, but if hard work has to be re-
sumed immediately afterwards, very frequently indigestion is the
result. It is the cause of that form of congestive dyspepsia to
which the middle classes in Germany are extremely subject, and
which drives them instinctively to eliminative mineral waters, like
swallows to the South.

The best time for an adult's largest meal is when the business
of the day is done, say, somewhere between five and eight. If it
is taken earlier, there is time to get hungry again before bed-time;
and if later, sleep comes too soon on the top of it. For light
eaters the later hours, for heavy eaters earlier hours are most suita-
ble. It may be observed that the court dinners of the city compa-
nies and the merry-makings of Greenwich ichthyophagists, where
the guests meet to eat largely, are usually early.

It is superfluous for a healthy person, not influenced by any of
the peculiar circumstances which will be hereafter considered, to
devote special attention to considerations concerning the whole-
someness or digestibility of his dinner. He is apt to leave off
this and leave off that, under the impression that they have once
disagreed with him, till his bill of fare becomes most injuriously
restricted. Variety in diet is of essential importance to health,
and a succession of several imperfect or even unwholesome kinds
of food is better than a monotonous repetition of a perfect aliment.
Occasional feasts and occasional fasts constitute the natural mode
of life for an intellectual and social animal. This paragraph ap-
plies to all meals, but I have inserted it apropos of dinner as being
the principal.

By variety is implied, not a great number of dishes at once,
which is confusing and oppressive, and destructive of the object
aimed at, but a frequent (why not daily ?)-difference in the princi-
pal dish, to which the few other accessory dishes are harmonized.
Some of the most appetizing dinners one has ever eaten have
really consisted of one article, novel and unexpected. The famous
Mrs. Poyser sagely remarked that a man's stomach likes to be
surprised, and no surprise is possible if the same monotonous
superfluity is repeated day after day.

In the course of the evening a cup of tea seems to give a fresh
fillip to digestion, and supplies liquid which is required for solu-

120 GENERAL DIETETICS.

tion of the viands. Some persons are afraid of its keeping them
awake, and will find a good substitute in extempore lemonade a
cup of hot water poured on a slice of lemon, some chips of the
rind, and a lump of sugar. But tea of an afternoon is by no
means to be recommended. The habit of taking it began as a
sort of fashionable whim about a dozen years ago, but spread so
far downwards through the middle classes that medical men
ought to exert themselves to stop it. If the dinner hour is so late
that too long a time interposes between it and luncheon, let the
latter be moved onwards, and, if necessary, breakfast also. For
the dilution and washing away of the gastric secretion weakens its
power of digesting the subsequent dinner, improperly blunts the
appetite, and not unfrequently generates flatulence and dyspepsia.
A biscuit, and an orange or an ice is a much less injurious indul-
gence at the same hour.

A man in health ought to be satisfied with three meals a day,
and should educate his stomach to take enough at them to supply
his requirements. The practice of constantly nibbling at odd
times induces a flow of saliva almost continuous, like that of her-
bivorous animals, and neutralizes the gastric juice, so that meat is
not fully digested.

The last meal should be sufficiently late for the whole not to be
absorbed before retiring to rest. Going to bed hungry is liable to
induce a habit of restlessness at night. If business or pleasure
keep you up much longer than usual, it is better to take a light
farinaceous supper, which, in this case, induces sleep. This, how-
ever, is a very different thing from sleep in a state of repletion,
which (as was before observed) disturbs the circulation in the
brain, producing painful dreams, unrefreshing rest, and feverish-
ness.

An average adult may consider that he is taking enough to
supply the ordinary requirements of healthy activity, if he eats in
twenty-four hours the equivalents of a pound of meat and two
pounds of bread. The English soldier, on home service, receives
from government f Ib. of meat and 1 Ib. of bread, and he buys
about Ib. additional bread and 1 Ib., or so, of other vegetable
food. 1 Dr. Parkes calculates that this quantity of nitrogenous ali-

1 Parkes, Practical Hygiene for Medical Officers of the Army, p. 523.

ON DIGESTION. 12i

merit is somewhat deficient for the maintenance of high vigor, so
that I have ventured to add J Ib. of animal food, reducing by a
few ounces the supply of vegetables.

The nearer a man approximates to this allowance the better, if
he has no individual peculiarities of size, temperament, occupa-
tion, climate, or state of health to allow for. To all but excep-
tional cases, anything beyond this is excess not hurtful necessa-
rily, perhaps even beneficial as an occasional change, but still an
excess. To continue such excess as a daily habit, puts a person
in a position more prone to ill health than he would be natu-
rally. To err by defect is equally injurious if persisted in; but
it has this advantage, that it oftener obtains a compensation
which to a considerable extent rectifies the balance. Thus, the
soldier at home, above quoted in illustration, gets frequent little
treats, partly out of his own and partly out of others' pockets,
which fill up the corners left by the government ration. And,
perhaps, the most perfect diet is one just within the limit pro-
posed, with an occasional transgression as a change.

It is possible, certainly, for a high liver to make an equivalent
change by abstinence ; and if he is lucky enough to be ill and go
to a doctor, he is perhaps advised to do so ; but I have never yet
known one to fast voluntarily as a preservative to health, though
he must have often felt the beneficial effects of its being forced
upon him. It is forced upon him, sometimes, as a direct conse-
quence of the habit of overeating; a surfeit of accumulation comes
on, or he brings it on by going a little further than usual, and
then nausea and loss of appetite perform the good office of mak-
ing a change by cutting off the supplies. Unless relieved in this
way, the high liver gets torpid and stupid by day, restless by
night, there is a sluggish circulation in the veins from the over-
loading of the blood with useless material, there are congestions
and engorgements of the internal organs, and dark dirty discolora- (
tions of the skin, thick urine, flying unaccountable pains, neural-
gia, rheumatism, gout, obesity.

The evils of too great restriction of food will be considered in a
future chapter, when we come to the subject of poverty as a modi-
fying circumstance in dietetics.

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