The facts just related bring forward a new aspect from which the

relative nutritive values of different foods may be judged. The older

criteria must frankly make room for the new or else be displaced by

them. Experiments upon the utilisation of food-stuffs, in which what

remains undigested is determined as well as what is absorbed into

the body fluids, cannot alone be trusted to solve the question in a

satisfactory manner. Suppose, for instance, that in the digestion of

a given food the alimentary canal has been given a certain work to

perform; if it be in health the work will be accomplished in the

best possible manner--that is to say, with complete abstraction of

everything nutrient. You will thus learn how much nutrient material was

contained in the food, but the question of its digestibility remains

as obscure as before. In your experiment you do not know how great an

effort it has cost the alimentary canal to extract all the nourishment

from the food. Nor can artificial digestion experiments settle the

question of digestibility, for experiments in which food is normally

partaken of are quite different from those in the test-tube, where

we have to deal with only one juice, and not with the interaction of

different juices and different food constituents. That one must here,

as a matter of fact, make a distinction is clear from the observation

of Dr. Walther in our laboratory. Fibrin, which is regarded by all as

the most easily digested proteid, proved, when compared with a nitrogen

equivalent of milk, to be a much stronger excitant of the pancreas,

although milk contains, in addition to nitrogenous substances, a good

deal of other non-nitrogenous material. The digestibility and nutritive

value of foods must obviously be decided by an estimation of the real

work which they entail upon the digestive apparatus, both in regard to

the quantity and quality of the juices poured out on a given amount

of nutrient material. The energy used up in gland metabolism must be

deducted from that of food taken in. The remainder will then indicate

the value of the food to the organism; that is to say, will give the

amount available for use by all the other organs exclusive of the

digestive apparatus. From this point of view those materials must be

taken as less nourishing and less digestible which are in large part

used up to make good the expenditure entailed by their digestion on

the part of the alimentary canal; that is to say, those food-stuffs

are less useful whose nutritive value little more than covers the cost

of their digestion; consequently, it is of great practical importance

to compare from this aspect the same foods differently prepared--for

example, boiled and roast meat, hard and soft boiled eggs, boiled and

unboiled milk, etc.

A discussion of some further medical questions may here be taken up.

The first concerns the therapeutic use of the neutral and alkaline

salts of sodium. In clinical, pharmacological, and physiological

text-books it is stated now, as ever, that these salts promote a flow

of gastric juice. We may look in vain, however, for any experimental

foundation to support this doctrine. The experiments brought forward

cannot be regarded as conclusive. When Blondlot sprinkled sodium

bicarbonate upon flesh, or Braun and Grützner introduced sodium

chloride solutions directly into the blood, they began with methods

either false in themselves or far removed from normal conditions. In

this case, however, the gaps in the experiment were happily made good

by the clinician, for the experiment appeared to be confirmatory of

clinical experience. That sodium salts (the chloride and bicarbonate)

are useful in disorders of the digestive apparatus there can be no

doubt. How do they act, however? It appears to me that here, as in

some other cases, medical science has fallen into error. When we

know that an effect takes place it does not by any means imply that

we know the mechanism by which it occurs; and although medicine is

broad enough and comprehensive enough to make free use of empiricism

in practice, yet it often thinks in narrow grooves when it turns to

the explanation of facts. It frequently tries to explain complicated

healing processes in the simplest way, on supposed physiological

data. And this is true in the present case, which affords an example

of prevalent medical reasoning; the alkalies work favourably in

digestive disturbances--therefore they are succagogues. Naturally

the stomach, under the influence of alkalies, sometimes begins to

secrete a greater quantity of juice. This means, however, that it

has recovered from a disordered state and has returned to normal

conditions. Consequently, the effect is due to the fact of recovery,

and not to a direct influence of the alkalies. This latter, however,

must be specially proved. The assistance afforded by the alkalies to

the organism might be capable of another explanation; for example,

that which is ordinarily given. In this case, however, I venture to

offer a reason for the effects of sodium chloride, and of the alkaline

salts of sodium, which is exactly the opposite of that generally

accepted. We were unable to convince ourselves of any succagogue

influence on the part of these salts. Indeed, both on the stomach

and pancreas they proved in our hands to have an inhibitory effect.

In addition to the experiments which I previously brought forward

concerning the relation of alkalies to gastric and pancreatic juice,

I may relate the following observation. A dog which fortunately had

survived the performance, one after the other, of a gastric fistula,

a pancreatic fistula, and an œsophagotomy, received daily during the

course of several weeks an addition of soda to its food. The animal

enjoyed good health and had an excellent appetite. When the first sham

feeding experiment was carried out, the relatively small effect of

this otherwise very active juice-exciting procedure at once struck

us. At the same time we observed that the pieces of flesh which fell

from the upper end of the œsophagus, contrary to the ordinary rule,

were hardly at all insalivated. In this dog, therefore, a greatly

lowered activity of several digestive glands--viz., of the gastric,

pancreatic, and salivary glands--simultaneously existed. With regard

to the salivary glands the circumstance was naturally submitted to

closer investigation. I believe that the inhibitory influence of the

alkalies on the digestive glands, which was here proved experimentally,

may furnish a basis for the following representation of their mode

of action in producing healing effects. Catarrhal affections of

the stomach are characterised by an incessant or very protracted

secretion of slimy, weakly acid gastric juice. Further, in many cases

the affection begins with a hypersecretion, that is an abnormal

excitability, of the secretory apparatus which makes itself evident in

a superfluous and useless flow. The same must be conceived to happen

in disorders of the pancreatic gland; at least such a condition sets

in after operations performed for physiological purposes. It is,

further, justifiable to suppose that, when an affection is once set

up by this or that cause, it may later maintain itself independently;

for continuous activity has undoubtedly a harmful influence on the

glands. The due nourishment, and the restoration of organs after

activity, proceeds best during rest. In the normal course of events,

after a period of active work follows a pause, during which the

latent work of restoration is accomplished. When, therefore, a remedy

effectively restrains the excessive work of a diseased organ, it may

in this way contribute to the removal of the pathological condition,

and thus to a restoration of the normal state. In this consists, in my

opinion, the healing effects of the alkalies. One might draw a parallel

between the action of these substances in digestive disturbances

and that of digitalis in compensatory disturbances of the heart. An

uncompensated heart beats rapidly, and thereby only aggravates its

condition. Its time of rest, that is of recovery, of restitution of

the organ, is shortened. A vicious cycle is set up. The weak action

of the heart lowers blood pressure; the lowering of this leads (from

known physiological causes) to an increase in the number of beats;

the quickening leads to weakening of the organ. Without doubt the

digitalis aids by breaking through this vicious cycle, in that it

greatly slows the pulse, and thereby gives new power to the heart. With

our explanation of the action of the alkalies harmonises the further

circumstance that, with the use of the salts in question, a strict diet

is generally prescribed, which means that a certain amount of rest is

secured for the digestive glands. It is interesting that in clinical

investigations with the stomach-tube, after a period when the alkalies

were looked upon as succagogues, a new phase has also set in, mention

being now more frequently made of a restraining effect.

The cause of the erroneous belief that alkalies promote a flow of juice

obviously lies in this, that people omitted to compare the effects

of the saline solutions with those of like quantities of water (_Dr.

Chigin_).

The second point which we may consider is the following. The chief

difficulty of the physician who wishes to regulate the diet of patients

when they suffer from digestive disturbances consists in the fact

that idiosyncrasy plays a very important _rôle_. In one and the same

illness, different patients react to the same diet in wholly different

ways. That which is agreeable to one, and is well borne and useful,

may be rank poison to another. Consequently, the golden rule in

dietetics is to give no directions with regard to food till one has

made inquiries concerning the inclinations and habits of the patient.

What does all this indicate? Till now physiology had no experimental

answer to the question. But our facts, it appears to me, contribute

to a clearing up of the situation. Every food determines a certain

amount of digestive work, and when a given dietary is long continued,

definite and fixed types of glands are set up which can only slowly

and with difficulty be altered. In consequence, digestive disturbances

are often instituted if a change be suddenly made from one dietetic

_régime_ to another, especially from a sparse to a rich diet; such, for

instance, as happens after the long Russian fasts. These disturbances

are expressions of the temporary insufficiency of the digestive glands

to meet the new demands made upon them.

Finally, it may be of some use to relate the following here. There

are often cases of sudden and unaccountable digestive disturbances.

From the standpoint of modern physiology they might be explained by

an activity of the secreto-inhibitory nervous system, which from some

cause or other has been excessively and abnormally stimulated. In any

case this system is now a factor of which the physician has to take due

account.

SWALLOWING AND MOVEMENTS OF THE STOMACH AND INTESTINES

BY W. B. CANNON, M.D.

_Of the Physiological Laboratory of the Harvard Medical School Boston,

Mass., U. S. A._

[NOTE.--In the beginning of 1896 Dr. Professor Henry Pickering

Bowditch, one of our Board of Scientific Assessors in the Nutrition

Case suggested the use of the Röntgen ray as a means of learning more

than was then known about the mechanism of swallowing. There was

much difference of opinion among research physiologists about this

important function, and the question was far from settled. Magendie

published a theory of deglutition, in Paris, in 1836, which was

practically accepted until 1876, when Dr. Professor Angelo Mosso, of

the University of Turin, Turin, Italy, established the theory of sole

peristaltic assistance in swallowing. Again in 1880 Dr. Professor

Kronecker, of Berne, Switzerland, in connection with Dr. Falk, and

later in connection with Dr. Meltzer, of New York, produced evidence

to prove a more complicated process in deglutition than that of

peristalsis alone. But even Kronecker and Meltzer found, as they went

on, evidence to modify their earlier beliefs, and hence the subject

was not cleared up to a point of general agreement.

The suggestion made by Dr. Bowditch was taken up in the Harvard

Physiological Laboratory and formed the beginning of a series of

studies of the mechanical factors in digestion. The reports of these

studies, presented by Dr. W. B. Cannon and collaborators, in the

_American Journal of Physiology_, in the volumes of 1898 and 1903,

are so understandable, even to the layman ignorant of physiological

nomenclature, that we are prompted to give them, almost entire,

leaving out only the technical description of the methods employed,

which are only interesting to research students who have access to the

_Journal_.

It will be noted that three of the professors of physiology

mentioned in connection with this preliminary study of the nutrition

problem--Bowditch, Mosso, and Kronecker--are members of our presently

organised Board.—HORACE FLETCHER.]

THE MOVEMENTS OF THE FOOD IN THE ŒSOPHAGUS

BY W. B. CANNON AND A. MOSER

_From the Laboratory of Physiology in the Harvard Medical School_

Extracts from _American Journal of Physiology_, 1898

The movements of deglutition, in common with many other physiological

processes, were explained by the older physiologists on anatomical

grounds. Thus, Magendie divided the act into three parts, corresponding

to the anatomical regions of the mouth, pharynx, and œsophagus. The

muscles of each of these divisions were considered the active agents

in propelling the food onward. The function of moving the mass to the

pharynx was variously ascribed to the tongue itself, to the mylohyoid

muscles, and to gravity. For the second part, the movement through the

pharynx, there was more unanimity of opinion, since the constrictors,

especially the middle and lower, were evidently concerned.

Direct observations on the movement of swallowed masses in the

œsophagus were first made by Mosso. The œsophagus of a dog was laid

bare, and a transverse incision made through it, or a piece of it

excised. A small wooden ball was placed in the canal below the excised

part, and the animal was then stimulated to swallow. One or two seconds

after the contraction of the pharyngeal muscles a peristaltic wave

began to traverse the œsophagus. This wave did not stop at the point of

excision, but in due time reappeared below, and carried the ball to the

stomach. Thus the act was shown to be controlled by the central nervous

system. Peristalsis was so plainly the motive power that the action was

never doubted. Yet this belief was soon to be questioned.

In 1880 Falk and Kronecker studied the movements in the mouth and

pharynx, and advanced the theory that deglutition was accomplished by

the rapid contraction of the muscles of the mouth. During the act of

swallowing the air-tight buccal cavity shows a manometric pressure of

twenty centimetres of water. The same pressure was demonstrated to be

present also in the œsophagus, but not in the stomach. This pressure

was considered sufficient to force food through the œsophagus before

the peristaltic wave traversed it. Another argument for rapid descent

was found in the fact that cold water can be felt in the epigastric

region almost immediately after being swallowed. Further, when strong

acids pass through the gullet, they corrode but small parts of it, and

not the entire mucous membrane, as would be the case were the acid

carried to the stomach by peristalsis.

Over a year and a half ago it was suggested by Prof. H. P. Bowditch

that if some substance opaque to the Röntgen rays were swallowed,

it could be seen in its passage to the stomach, and the nature of

its movement thus determined. Anæsthesia could be dispensed with,--a

desirable condition, since observers had found that it interfered

greatly with the deglutition reflex. It would be unnecessary to open

either the abdominal or the pleural cavity. The reflex stimulus of

food, moreover, would be better than electrical stimulation of the

superior laryngeal nerve. In short, the animal would swallow normal

food under practically normal conditions. At Dr. Bowditch’s suggestion

and with his valuable assistance--which we gratefully acknowledge--we

made the following series of experiments.

To render the swallowed mass opaque, subnitrate of bismuth was used.

The salt is tasteless, practically inert, and can be fed in large

quantities without harm. In order that observations could be made by

more than one person, all experiments were conducted in a dark room. On

the side of the animal opposite the Crookes tube was placed an open

fluorescent screen, on which the different tissues of the animal were

outlined with varying degrees of light and shade. Among these shadows

the swallowed mass appeared as a darker object, and thus its motion

could be studied.

For the first experiments the goose was selected. The head and neck

were held stationary by a tall pasteboard collar, which allowed free

movement of the head without constriction of the neck. The fluorescent

screen was placed against this collar at a uniform distance of thirty

centimetres from the tube. When a bolus of corn-meal mush mixed with

bismuth was placed in the pharynx, it descended slowly and regularly,

and occupied about twelve seconds in passing over a distance of fifteen

centimetres. The screen was marked at intervals of two centimetres with

cross lines, by means of which the relative rate in different parts of

the œsophagus could be studied. A vibrator marking tenths of a second

was interrupted whenever the bolus crossed a line. An average of over

one hundred such observations showed that the rate became slightly

slower as the bolus proceeded.

In order to test liquids, molasses was mixed with bismuth to such a

consistency as to drop easily from a glass rod. When this was fed

with a pipette, it passed slowly and regularly down the œsophagus,

clearly by peristalsis. The rate was about the same as for solid food.

In both these experiments the addition of water would sometimes cause

irregularities in the descent. Microscopic sections from four different

parts of the œsophagus of the goose showed no histological difference.

In the experiments on the cat, the animal was placed on its back and

left side on a holder. The extremities were secured by straps. The

head was held between two upright rods, connected above by a thong;

this allowed free movement of the head, without resistance to the

passage of food. Shreds of meat dipped in bismuth were ordinarily

masticated and swallowed without difficulty. For soft solids, bread and

milk were used, so fluid as to be easily drawn up into a pipette. The

insolubility of the bismuth salt rendered the study of liquids more

difficult. Strong solutions of potassic iodide and other salts, and

suspension of bismuth, in acacia and molasses were tried; but a simple

mixture of milk and bismuth, shaken in a test tube and immediately

drawn up into a pipette, was found most practicable.

Inasmuch as the movement of these different foods varied in different

parts of the œsophagus, it will be convenient to divide the latter into

three sections. The first or cervical portion extends from the pharynx

to the thorax; the second or thoracic, from here to the lower half of

the heart; and the third comprises the rest of the canal. The relative

length of these three parts is about in the ratio of 9:8:6.

The beginning of deglutition was noted by one observer by a finger on

the larynx; the same observer called out when the bolus arrived at

the thorax, heart, and stomach respectively, while the other observer

noted the time. The movement of solids will first be considered. The

descent the entire way was by peristalsis, but the rapidity varied. The

duration of the movement in the cervical portion was two and a half

seconds, and in the thoracic region a little less than two seconds.

At the lower end of the heart there was sometimes a slight pause. In

the lower section, from the heart to the stomach, the movement was

decidedly different; the rate was always very slow. The distance was

less than one-third of the entire canal, yet the time consumed in this

part ranged from six to seven seconds, or three-fifths of the entire

time of descent. The character of the movement here was also peculiar.

Whereas in the upper sections the passage was uniform and regular, with

a slight acceleration in the thoracic region, here it was apparently

irregular, for the bolus descended about one centimetre with each

inspiratory movement of the diaphragm, and remained stationary or

descended very slightly during expiration. Thus a series of hitches

seemed to carry the bolus to the cardia. A probable explanation of this

peculiar movement is that the stomach and lower œsophagus were pulled

down with each descent of the diaphragm. This would make the movement

appear irregular, although it was really a slow peristalsis. It may be

well to remark here that this movement was invariably observed in the

cat with every kind of food.

Semi-solids, namely, a mush of bread and milk, descended in the same

way as solids; but the rate was slightly faster in the upper œsophagus,

for the bolus took about a second less to reach the cardiac level. From

here the rate was the same as with solids.

For liquids, one and a half to two seconds sufficed for the descent to

the midheart region. Here there often occurred a long pause, from a few

seconds to a minute or more. Then the œsophagus apparently contracted

above the liquid, which slowly passed on to the stomach, as already

described. Sometimes it seemed as if a swallowing movement, evidenced

by a rise of the larynx, started the peristaltic wave. Again, several

swallows would succeed one another before the liquid passed on. A few

times the bismuth and milk seemed strung out along the œsophagus;

some more liquid descending would gather this up, and the whole mass,

assuming an ovoid form, would move into the stomach.

Thus in the cat the total time for deglutition varies from nine to

twelve seconds. The lowest section presents no change ascribable to a

difference in consistency, while in the upper sections the rate does

slightly increase with the more liquid character of the food.

In experiments on the dog, bismuth enclosed in capsules or wrapped in

shreds of meat was fed as the solid. The general phenomena were as

follows: With the rise of the larynx there was a quick, propulsive

movement of the bolus, which descended rapidly for a few centimetres,

sometimes as far as the clavicle. From this point the rapidity

was diminished, yet no pause was observed; the bolus simply moved

more slowly. This rate was then continued to the stomach without a

slackening of speed in the diaphragmatic region, as was observed in the

cat. Semi-solids moved in the same way as solids. The total time of

descent from larynx to stomach was from four to five seconds.

Liquids gave even a more decided squirt in the beginning of the

movement. To render the œsophagus as lax and free as possible, the

head of the dog was released from the upright rods and held by the

hands after the food was placed in the mouth. Sometimes the liquid

descended rather rapidly as far as the heart, at other times no further

than the clavicle; then without a pause it passed on slowly and

regularly, reaching the stomach in about the same time as solids and

semi-solids.

Thus in the dog and cat but little variation was seen in the swallowing

of liquids and solids. The liquids pass somewhat faster in the upper

œsophagus. But in some animals the difference of rate with foods of

varying consistency is much more marked. In the horse, for instance,

mere observation shows a decided variation in the rate of movement

in the œsophagus. Liquids shoot along the gullet, while solids move

clearly by peristalsis. To determine the rate of solids, one hand was

placed on the larynx of a horse to note the beginning of swallowing,

and the other hand near the shoulders, where the bolus could be easily

felt in its passage. The time consumed by the bolus in passing over a

certain distance was measured by a stop watch. The rate obtained for

solids, such as hay or grain, was from thirty-five to forty centimetres

a second.

For semi-solids, a mixture of bran and water was made, thin enough to

run easily between the fingers. Each bolus was watched by a separate

observer with a separate watch. The average rate obtained was the same

as for solids.

Liquids in the horse pass with a rapidity too great to be affected

by peristalsis. Another force must be sought. Among the various

muscles supposed to be effectual in moving food into the pharynx, the

mylohyoids were shown by Meltzer to be essential. The styloglossi were

cut by him without much interference with deglutition, but section of

the mylohyoid nerves rendered the act impossible. The activity of these

muscles in the horse during swallowing is easily perceived by the hand.

Their energetic contraction is a sufficient explanation of the rapid

passage of water through the œsophagus. The motion here is more than

five times as rapid as that of solids and semi-solids.

Meltzer’s experiment to measure the rate of liquids in man by

passing a stomach tube containing litmus paper was repeated by us

with some modifications. Congo red paper was used, since it is more

sensitive than litmus; it also furnishes a means of differentiating

between mineral and organic acids, as the discolouration produced

on Congo red by mineral acids is removed by ether. It was thus

possible to distinguish between the discolouration produced by

gastric regurgitation and that produced by the swallowed liquid. For

the swallowed liquid, one-half per cent lactic acid was found most

satisfactory, as the colour produced by it on Congo red test paper is

almost instantly discharged in ether. By this method the paper was

found discoloured within half a second after the rise of the larynx,

certainly too short a period for a peristaltic wave to carry the liquid

to the neighbourhood of the cardia.

The X-ray method lends itself less successfully to the study of

deglutition in man than in the other animals we have studied. The

thickness of the thorax, the distance of the œsophagus from the

surface, and the relation to dense tissues render the observation of a

swallowed mass difficult, especially when the mass is in rather rapid

motion. The few observations which we have to report were made on a

seven-year-old girl, placed in the sitting posture. Gelatine capsules

containing bismuth were used for solids, and were traced to a point

below the heart. The motion was very regular, and apparently due to

peristalsis, for the bolus descended without a hitch or irregularity of

any kind. Sometimes the capsule became fixed in the upper œsophagus,

at about the level of the second rib. Repeated swallows of water would

fail to dislodge it. An interesting point was noted here. With each

attempt at swallowing, the capsule would rise slightly, as if the

œsophagus was pulled up with the rise of the larynx; then the capsule

would descend to its former position.

Semi-solids--a mush of bread and milk--could be seen about as far as

solids; that is, to just below the heart. The motion of the mushy bolus

was the same as with solids, except that the rapidity was perhaps

slightly greater.

It should be noted here that with the human subject, as well as with

the horse, our results for semi-solids differ from those derived by

Meltzer’s method; for according to his statements semi-solids, like

liquids, are squirted down the œsophagus, and are not propelled by

peristalsis, as has been the case in our observations.

Liquids--bismuth and water--were seen only in the neck and upper

thorax. Here there was a decided squirt. With the rise of the larynx

the liquid was seen to pass rapidly through the pharynx and well down

into the thoracic œsophagus before it was lost to observation. The

rate, however, by estimation was less than that of liquids in the horse.

There remains to be considered Meltzer’s latest investigation, in

which he endeavoured to ascertain whether liquids remain above the

cardia till the arrival of the peristalsis, or ooze down before. An

experimental answer was secured by Meltzer by the following method. The

abdominal and gastric walls of an anæsthetised dog were incised, and a

tube (vaginal speculum) introduced. Through this the entrance of food

into the stomach could be observed directly. In repeated experiments no

liquid was seen to pass through the cardia before the arrival of the

peristaltic wave. An incision through the diaphragm near its anterior

origin showed that the swallowed liquid was not squirted as far as a

point an inch above the diaphragm. To observe the œsophagus nearer its

beginning, the upper three ribs were resected on the left side. Thus

the swallowed liquid was seen to shoot along the œsophagus before any

peristalsis reached this point. The resection of the fifth rib exposed

the œsophagus half-way between the bifurcation of the trachea and the

diaphragm. Here a bulging was sometimes observed immediately after

the beginning of the act, and the swallowed mass remained there until

a peristaltic wave carried it down. If the mass swallowed was small,

or was projected with moderate force, it might not even reach as far

as the bifurcation. From these experiments Meltzer concluded that in

animals, as in man, liquid food is not carried down the œsophagus by

peristalsis, but is thrown rapidly into a deep part of the canal. The

depth reached depends on the quantity swallowed, the force used, and

the tonicity of the lower part of the œsophagus.

The difference between these methods of Meltzer and those employed in

our experiments has already been mentioned; and merely his results,

which were obtained with liquids alone, need be considered here.

According to our observations on the dog, there was no distinct pause

at any part of the canal. The movement simply became slower, and

continued at this rate until the stomach was reached. Neither was

the rate through the diaphragmatic part of the œsophagus slower than

through the thoracic. The quick propulsive movement noticed in the

dog was observed with solids and semi-solids as well as with liquids,

but the liquids descended further down the canal before the movement

changed to the slower peristalsis. While this difference was evident to

the eye, the total time consumed by liquids in passing from pharynx to

stomach was not enough shorter than the time for solids and semi-solids

to be determined by our measurements.

SUMMARY.

The phenomena of œsophageal deglutition as determined by our

experiments may then be described as follows:—

There is a difference in swallowing according to the animal and the

food which is used.

In fowls the rate is slow and the movement always peristaltic, without

regard to consistency. A squirt-movement with liquids is manifestly

impossible, as the parts forming the mouth are too hard and rigid. With

this diminution of propulsive power in the mouth there is observed a

greater reliance on the force of gravity. The head is raised each time

after the mouth is filled, and the fluid by its own weight trickles

into the œsophagus, through which it is carried by peristalsis.

In the cat the movement is always peristaltic, and slightly faster than

in fowls. A bolus takes from nine to twelve seconds in reaching the

stomach. Liquids move somewhat more rapidly than semi-solids in the

upper œsophagus. In the lower or diaphragmatic part the rate is very

much slower than above, and is the same for liquids as for solids.

In the dog the total time for the descent of a bolus is from four

to five seconds. The food is always propelled rapidly in the upper

œsophagus, and moves more slowly below. This rapid movement is

frequently continued further with liquid food. No distinct pause was

observed when the movement of the bolus changed from the rapid to the

slower rate.

In man and the horse liquids are propelled deep into the œsophagus at a

rate of several feet a second by the rapid contraction of the mylohyoid

muscles. Solids and semi-solids are slowly carried through the entire

œsophagus by peristalsis alone.

THE MOVEMENTS OF THE STOMACH STUDIED BY MEANS OF THE RÖNTGEN RAYS

BY W. B. CANNON, M.D.

_From the Laboratory of Physiology in the Harvard Medical School_

Extracts from _American Journal of Physiology_, 1898

Since the stomach gives no obvious external sign of its workings,

investigators of gastric movements have hitherto been obliged to

confine their studies to pathological subjects or to animals subjected

to serious operative interference. Observations made under these

necessarily abnormal conditions have yielded a literature which is

full of conflicting statements and uncertain results. The only sure

conclusion to be drawn from this material is that when the stomach

receives food obscure peristaltic contractions are set going, which

in some way churn the food to a liquid chyme and force it into the

intestines. How imperfectly this describes the real workings of the

stomach will appear from the following account of the actions of the

organ studied by a new method. The mixing of a small quantity of

subnitrate of bismuth with the food allows not only the contractions

of the gastric wall, but also the movements of the gastric contents

to be seen with the Röntgen rays in the uninjured animal during normal

digestion. An unsuspected nicety of mechanical action and a surprising

sensitiveness to nervous conditions have thereby been disclosed.

INTRODUCTORY LITERATURE

The early writings on the subject of gastric movements are

characterised by general inferences from physical laws and from the

anatomical structure of the stomach. According to Galen the stomach

had four functions: to draw the food from the mouth (_facultas

attractrix_), to retain the food (_facultas retentrix_) during the

process of chemical digestion (_facultas alteratrix_), and, finally,

to pass the changed material onward (_facultas expultrix_). In later

writings the _facultas attractrix_ failed to appear as one of the

functions of the stomach. Fallopius, in the sixteenth century, changed

the notion of the _facultas retentrix_ by suggesting that the pylorus

alone performed this office, and that the muscles of the gastric wall

could help only by remaining quiet. Thus the _facultas alteratrix_ and

the _facultas expultrix_ are left as true gastric functions. It is with

the latter activity and its effects that this paper is concerned.

The ideas of the early writers concerning the pylorus and cardia are

of interest. The cardia, they were agreed, is closed during normal

digestion in order to keep the food from re-entering the œsophagus. The

pylorus they looked upon as the ruler of the actions of the stomach.

Such names as pylorus (keeper of the gate), janitor justus, and rector,

which the first investigators gave to the sphincter, indicate their

theories of its functions. The passage of chyme into the duodenum, the

keeping of undigested food in the stomach, the act of vomiting, were

all dependent, they believed, on the “will” of the pylorus.

No substantial advance was made beyond these hypotheses until the

beginning of the eighteenth century, when Wepfer and Schwartz applied

the experimental method to the study of the gastric movements and laid

the foundation of a more accurate knowledge. Wepfer vivisected wolves,

dogs, and cats, and observed constrictions following stimulation of

the stomach. He remarked a general contraction of the pyloric part in

vomiting and noted peristaltic and antiperistaltic movements passing

over the organ. About the middle of the stomach he frequently saw a

deep constriction. The investigations of Schwartz are more valuable in

that his search was for the normal action of the muscular coats. The

movements, as he observed them, were generally only slight. They began

either at the pylorus and passed to the left, half-way to the cardia,

or started at the fundus and went to the pylorus. The contractions

and relaxations, following one another, formed larger or smaller

depressions and elevations, _i. e._, more or less definite waves.

Near the middle of the last century Haller, after confirming the

results obtained by Schwartz and Wepfer, summarised his knowledge of

the motor functions of the stomach as follows. In general, contraction

alternates with relaxation, so that the stomach is, now here, now

there, made narrower by longitudinal or transverse depressions; then

in these same places relaxation and bulging occur. So long as both

apertures are closed the food is driven hither and thither by the

shifting movements. It first takes a definite direction when the cardia

or the pylorus opens. If the cardia opens, there is an antiperistalsis

followed by regurgitation and vomiting. If, on the contrary, the

pylorus relaxes, a contraction, starting at the œsophagus, pushes the

contents of the stomach into the duodenum. The pylorus allows the

passage of fluids, but if it be stimulated by over distention or by

hard pieces of food, it closes tightly.

Such was the knowledge of gastric movements in Haller’s time. A

comparison of his descriptions with those in any standard work on

physiology published ten or fifteen years ago will show that, despite

very many researches, little advance had been made. Examinations

of animals and men with gastric fistulas, studies of the stomach

through the atrophied abdominal wall, and vivisection have yielded

numerous results; but these have not been harmonious, and have led to

much controversy. Prominent in this mass of material as a valuable

contribution are Beaumont’s careful observations through the gastric

fistula of Alexis St. Martin. Beaumont’s work has recently been

confirmed by Hofmeister and Schütz, who, with Rossbach, Hirsch,

Openchowski, and others, have presented during the last twelve years

much new and interesting information. Since, however, it will conduce

to clearness to set forth the results of these investigations in

connection with my own work, their consideration will be deferred until

later.

It will then appear that these later investigations, like the earlier

researches, disagree as to the details of the stomach movements.

Such differences in results are the proper outcome of the abnormal

conditions under which the studies have been conducted. Obviously, in

order to see the natural movements of the stomach, the organ should be

observed in its natural state, and not after it has been disturbed by

removal from the abdomen, or by the adhesions and losses of substance

incident to gastric fistulas.

As a means of watching the gastric motor activities under normal

circumstances, Dr. H. P. Bowditch, in the autumn of 1896, suggested the

use of the Röntgen rays. The present paper is the result of the work

thus far completed. The kind assistance and stimulating counsel of Dr.

Bowditch throughout the investigation are gratefully acknowledged.

THE ANATOMY OF THE STOMACH AND ITS RELATIONS TO THE SHADOW

It must be constantly borne in mind that the shadows described in this

research are cast by the gastric contents, not by the stomach itself.

Therefore the movements of the organ are not seen directly, but are

indicated by their effect on the contained food. Variations in the

length and breadth of the stomach can be inferred from changes in the

outline of the shadow, but variations in the front-to-back diameter of

the organ must be judged from changes in the intensity of the shadow.

The form of the active stomach soon after food has been taken is shown

in outline in Figure 1. Since the several parts of the stomach are

to be mentioned frequently, it will be well to recall them here in

their relations to the outline. The larger, cardiac part of the organ

lies to the left of a line through _w x_. Into it the œsophagus opens

through the cardiac sphincter, or cardia, at _c_. The pyloric part,

which includes all of the stomach situated at the right of a line _w

x_, is closed by the pylorus at _p_. This part has two divisions: the

antrum at the right of the line _y z_, and the preantral part of the

pyloric portion, or middle region of the stomach, between the lines _w

x_ and _y z_. The lesser curvature corresponds approximately to the

anterior border of the shadow _c w p_; the greater curvature to the

more extensive sweep, _c p_, along the posterior border.

[Illustration: FIGURE 1.]

The wall of the cat’s stomach consists of three coats, but as this

paper deals only with the functions of the muscular coat, that alone

will be described. The gastric muscular fibres are disposed in three

sets: an outer longitudinal layer, a middle circular layer, and a set

of inner oblique fibres. The longitudinal fibres continue those of the

œsophagus, and, radiating over the cardiac end, become more marked

along the curvatures than on the front and back surfaces. Over the

antrum they lie in a thick, uniform layer. The circular fibres form a

complete investment, and are arranged in rings at right angles to the

curved axis of the stomach. Towards the pyloric end they become denser

and stronger, and at the pylorus form a thick bundle, the pyloric

sphincter. Separating the antrum from the rest of the stomach, at _y

z_, is a special thickening of the circular fibres, called by the

early writers the “transverse band,” and described by Hofmeister and

Schütz as the “sphincter antri pylorici.” The oblique fibres start

from the left of the cardiac orifice and pass as two strong bands

along the anterior part of the dorsal and ventral surfaces, giving off

fine fasciculi to the circular musculature; towards the antrum they

gradually disappear.

The musculature of the stomach consists of smooth muscle fibres,

the chief physiological characteristics of which are slowness of

contraction, rhythmic alternation of contraction and relaxation, and

a very great tonicity, or power of prolonged contraction. The action

of these muscles in the process of gastric digestion is now to be

considered.

THE NORMAL MOVEMENTS OF THE STOMACH

Since the time of Haller the chief contributors to the knowledge of the

mechanics of the stomach have been Beaumont, Hofmeister and Schütz, and

Rossbach.

Beaumont’s famous investigations on Alexis St. Martin are recorded in

almost all general works on physiology. Through a gastric fistula he

introduced a thermometer-tube and observed how it was affected by the

motions of the stomach. His conclusions are as follows: “The circular

or transverse muscles contract progressively from left to right. When

the impulse arrives at the _transverse band_, this is excited to a more

forcible contraction, and closing upon the alimentary matter and fluids

contained in the pyloric end, prevents their regurgitation. The muscles

of the pyloric end, now contracting upon the contents detained there,

separate and expel some portion of the chyme.... After the contractile

impulse is carried to the pyloric extremity, the circular band and all

the transverse muscles become relaxed, and a contraction commences in a

reversed direction, from right to left, and carries the contents again

to the splenic extremity to undergo similar revolutions.”

In close accord with Beaumont’s description of the activities of the

human stomach are the records of the investigations on the stomach

of dogs by Hofmeister and Schütz. They removed the stomach from the

body and placed it in a moist chamber, kept at body-heat and covered

with glass. Under such conditions the organ remained active for from

sixty to ninety minutes. A typical movement is described by these

observers as composed of two phases. In the first phase a constriction

of the circular fibres, deeper on the greater curvature, starts a

few centimetres from the cardia and passes towards the pylorus. As

the constriction proceeds it increases in strength until a maximum

is reached about two centimetres in front of the antrum. This

annular contraction, called by Hofmeister and Schütz the “preantral

constriction,” closes the first phase. Immediately thereafter the

strong sphincter antri pylorici, or transverse band, contracts. Now,

while the preantral constriction is relaxing, the sphincter antri

pylorici tightens still more, and the antrum is shut off from the rest

of the stomach. As soon as this has occurred a general contraction of

the muscles of the antrum follows. Relaxation begins at the sphincter

antri pylorici and progresses slowly towards the pylorus; it is

sometimes accompanied by an antiperistaltic movement.

Although Rossbach also used dogs, his results vary considerably from

those of Hofmeister and Schütz. This discrepancy is possibly accounted

for by a difference in method, for Rossbach left the stomach in the

body. The dogs were treated with morphia and curare, and the abdomen

was then widely opened, so that the movements could be clearly seen.

When the stomach was full Rossbach saw deep constrictions begin near

the middle and pass in waves to the pylorus. At first these movements

were weak; later, however, they became more vigorous. The fundus

remained in tonic contraction about its contents and took no part in

the peristalsis.

Before attempting to explain the difference in the records of these

observers I shall give an account of what may be seen in a cat by use

of bismuth subnitrate and the Röntgen rays.

1. _Movements of the pyloric part._--Within five minutes after a cat

has finished a meal of bread, there is visible near the duodenal end

of the antrum a slight annular contraction which moves peristaltically

to the pylorus; this is followed by several waves recurring at regular

intervals. Two or three minutes after the first movement is seen very

slight constrictions appear near the middle of the stomach, and

pressing deeper into the greater curvature, course slowly towards the

pyloric end. As new regions enter into constriction, the fibres just

previously contracted become relaxed, so that there is a true moving

wave, with a trough between two crests. When a wave swings round the

bend in the pyloric part the indentation made by it deepens; and as

digestion goes on the antrum elongates and the constrictions running

over it grow stronger, but until the stomach is nearly empty they do

not entirely divide the cavity. After the antrum has lengthened, a

wave takes about thirty-six seconds to move from the middle of the

stomach to the pylorus. At all periods of digestion the waves recur at

intervals of almost exactly ten seconds. So regular is this rhythm that

many times I have been able to determine within two or three seconds

when a minute had elapsed simply by counting six similar phases of the

undulations as they passed a given point. It results from this rhythm

that when one wave is just beginning several others are already running

in order before it. Between the rings of constriction the stomach is

bulged out, as shown in the various outlines in Figures 2, 3, 4, and 5.

The number of waves during a single period of digestion is larger than

might possibly at first be supposed. In a cat that finished eating

fifteen grams of bread at 10.52 A.M., the waves were running regularly

at 11.00 o’clock. The stomach was not free from food until 6.12 P.M.

During that time the cat was fastened to the holder at intervals of

half an hour, and the waves were always observed following one another

in slow and monotonous succession. At the rate of three hundred and

sixty an hour, approximately two thousand six hundred waves passed over

the antrum during that single digestive period.

From the above review it will be manifest that my observations of the

movements of the pyloric part agree closely with those of Rossbach,

but differ considerably from the harmonious results of the work of

Beaumont, and Hofmeister and Schütz. Beaumont’s methods, however, may

be justly criticised on the ground that the thermometer-tube which he

held in the stomach was wholly unlike food and very liable to bring

about unwonted contractions in so sensitive an organ as the stomach.

Further, the movements observed by Hofmeister and Schütz, as Ewald has

pointed out, may easily have resulted from the abnormal stimulus due

to lack of blood--a potent cause of peristalsis. And it will be shown

later that the accounts given by these investigators describe very well

the actions of the stomach when stimulated by an unusual irritant.

In this connection it may be added that since the publication of the

preliminary notice of my work, Roux and Balthazard, using the Röntgen

rays, have published the results of observations on the stomachs of the

dog and man similar to those thus far described in this paper.

The fact that my observations and those of Roux and Balthazard

were conducted under normal conditions, and that the conditions of

Rossbach’s experiments were more nearly normal than those of the other

observers mentioned, warrants the conclusion that the pyloric part has

a more important function than that of merely expelling the contents

of the stomach into the intestines. After summarising the description

given by Hofmeister and Schütz, Ewald, for _a priori_ reasons,

declares: “I cannot accept this view. The plain fact that the pyloric

portion secretes a strongly digesting fluid containing pepsin and

hydrochloric acid proves it to be an important part for the peptonising

function of the stomach.” The account of the remarkable manner in which

the pyloric portion performs this function must be deferred until the

movements of other parts of the stomach have been considered.

2. _Movements of the pyloric sphincter._--Rossbach mars his otherwise

careful work by declaring that the pylorus is tightly closed during

the whole digestive period of from four to eight hours, and that then

the sphincter relaxes and the peristaltic waves empty the stomach.

That this is not the normal action of the sphincter has been shown

by several observers. Hirsch watched dogs with duodenal fistulas and

saw food come from the stomach at intervals of one-fourth of a minute

to several minutes. Roux and Balthazard maintain that in dogs food

enters the duodenum at the completion of each wave of constriction.

Observations on the cat, however, do not support their view, but agree

rather with the statement of Hirsch.

In cats fed with bread mixed with subnitrate of bismuth, ten or

fifteen minutes elapse after the first constriction in the antrum

before any food can be seen in the duodenum. When food does appear

it is spurted through the pylorus and shoots along the intestine for

two or three centimetres. Not every constriction-wave forces food

from the antrum. On one occasion, about an hour after the movements

began, three consecutive waves were seen, each of which squirted food

into the duodenum. The pylorus remained closed against the next eight

waves, opened for the ninth, but closed once more against the tenth and

eleventh. For each of the four succeeding waves the sphincter relaxed,

but blocked the food brought by three constrictions that followed; and

in this irregular way the food continued passing from the stomach. Near

the end of gastric digestion, when the constrictions are very deep, it

may be that the pylorus opens for every wave.

When a hard bit of food reaches the pylorus, the sphincter closes

tightly and remains closed longer than when the food is soft. This

action of the sphincter was shown by giving with the regular food of

the cat a dry, hard pellet of equal parts of starch paste and bismuth

subnitrate about the size of a pea. The food itself contained merely

enough bismuth to throw a dim shadow, near the centre of which the

pellet could be clearly seen as a dark object. The continual passing of

the contraction-waves finally brought the little ball to the pylorus.

When it arrived there, five grams of bismuth subnitrate were introduced

into the stomach through a tube in the œsophagus. This was done in

order that the food passing into the intestines after the ball came to

the pylorus might be distinguished from that which had gone on before.

By kneading the stomach the bismuth was distributed, as shown by the

uniformly black shadow. The pellet could still be seen near the end of

the antrum when the constrictions passed over it. Now, although the

waves continued to run regularly, the very black food did not gather in

the intestines in sufficient amount to be recognised until forty-two

minutes after it had been introduced. And when, finally, the food did

show itself in the intestines, its shadow contrasted strongly with that

of the food which had already passed on. The slowness of the expulsion

is not to be regarded as wholly due to the hard mass. No doubt the

kneading of the stomach mixed the contents of different parts of the

organ and brought to the pylorus food not yet sufficiently digested

to be passed by that selective sphincter. But this does not explain

the whole delay. Food similar to that given here, except that it

contained no hard particles, has usually been seen as small masses in

the intestines within fifteen minutes after being swallowed. A part of

the delay was evidently, therefore, caused by the hard pellet. Further

evidence on this point was secured when, on one occasion, the sphincter

was seen to open only seven times in twenty minutes following the

arrival of a hard particle of food at the pylorus. The conclusion may

therefore be drawn that hard morsels keep the pylorus closed and hinder

the passage of the food into the duodenum.

3. _Activity of the cardiac portion._--The part played by the fundus

apparently has not hitherto been properly appreciated. It has been

regarded as the place for peptic digestion, or as a passive reservoir

for food; but it is in fact a most interestingly active reservoir.

[Illustration: FIGURE 2.]

[Illustration: FIGURE 3.]

[Illustration: FIGURE 4.]

[Illustration:

FIGURE 5.--Figures 2, 3, 4, and 5 present outlines of the shadow

of the contents of the stomach cast on a fluorescent screen by the

Röntgen rays. The drawings were made by tracing the outline of the

shadow on tissue paper laid upon the fluorescent surface, and are

about one-half the actual size. They show the change in the appearance

of the stomach at intervals for half an hour, from the time of eating

until the stomach is nearly empty.

]

The action of the cardiac portion will be best understood by comparing

the appearances the stomach presents at various stages in a digestive

period. In order to show these stages I carefully made a set of three

tracings of the outlines of the stomach as soon as possible after a

cat had finished eating, and another set of three every half hour

thereafter, until the contents had disappeared (Figs. 2, 3, 4, and

5). These tracings were made by placing white tissue paper over the

fluorescent screen, and drawing with a thick lead pencil, easily seen,

as much of the boundary of the stomach as I could at the end of each

expiration. Between the times for making the drawings the cat was

allowed to rest quietly on a mat, but care was taken to lay her in the

same position on the holder for every drawing. The drawings of each set

were afterwards fastened over one another, so that the lines coincided

as closely as possible. Another piece of tissue paper was then put over

these, and all four sheets were laid on an illuminated pane of glass.

It was thus easy to get a composite tracing which, considering the

movement imparted to the stomach by respiration, and the dimness of

the shadows in the later stages of digestion, probably represents more

exactly than any single drawing the outline of the stomach for each

successive period.

A comparison of these drawings shows that as digestion proceeds the

antrum appears gradually to elongate and acquire a greater capacity,

and that the constrictions make deeper indentations in it. But when the

fundus has lost most of its contents, the longitudinal and circular

fibres of the antrum contract to make it again shorter and smaller.

Its change of form, however, compared with the rest of the stomach, is

slight.

The first region to decrease markedly in size is the preantral part

of the pyloric portion. The peristaltic undulations, caused by the

circular fibres, start at the beginning of this portion, and gradually,

by their rhythmic recurrence, press some of the contents into the

antrum. As the process continues, the smooth muscle fibres with their

remarkable tonicity contract closely about the food that remains, so

that the middle region comes to have the shape of a tube (Figs. 3 and

4--1.30 P.M. to 2.30 P.M.), with the rounded fundus at one end and the

active antrum at the other. Along the tube very shallow constrictions

may be seen following one another to the pylorus.

At this juncture the longitudinal fibres which cover the fundus like

radiating fingers, and the circular and oblique fibres reaching in

all directions about this spherical region, begin to contract. Thus

the contents of the fundus are squeezed into the tubular portion.

This process, accompanied by a slight shortening of the tube, goes on

until the shadow cast by the fundus is almost wholly obliterated (Fig.

5--5.30 P.M.).

The waves of constriction moving along the tubular portion press the

food onward as fast as they receive it from the contracting fundus, and

when the fundus is at last emptied they sweep the contents of the tube

into the antrum (Fig. 5--5.00 P.M. to 6.00 P.M.). Here the operation is

continued by the deeper constrictions till, finally (in this instance

at 6.12 P.M.), with the exception of a slight trace of food in the

fundus, nothing is to be seen in the stomach at all.

The food in the fundus may possibly be slightly affected by the

to-and-fro movements of the diaphragm in respiration. With normal

breathing the upper border of the cardiac portion swings through about

one centimetre; with dyspnœa, or deep breathing, through one and a half

or two centimetres. Since the lower border does not move so much, the

contents are gently pressed, and then released from pressure, at each

respiration. The pyloric portion is moved very little by the diaphragm,

the oscillation being less than a half centimetre.

Moritz has pointed out the value of an organ like the stomach for

holding the bulk of the food and serving it out a little at a time, so

that the intestines may not become congested during their digestive and

absorptive processes. All of the advantages supposed to be thus secured

to the intestines may be claimed also for the stomach itself. For

the preceding description indicates, and experiments to be described

later prove, that the stomach is composed of two physiologically

distinct portions: the busy antrum, over which during digestion

constriction-waves are running in continuous rhythm; and the cardiac

part, which is an active reservoir, pressing out its contents a little

at a time as the antral mechanism is ready to receive them.

THE MOVEMENTS OF THE STOMACH IN VOMITING

The appearance of the stomach during vomiting has been studied

particularly by Openchowski. He says that when an emetic is given

there follows a quivering of the stomach-wall, which, beginning near

the pylorus, shows itself later in the antral and middle regions of

the stomach. The quivering afterwards passes into a contraction, most

strongly marked in the antral part, since the peristaltic waves running

down to the antrum from above are continually growing deeper. At the

same time the fundus expands spherically. The increased contraction in

the pyloric part drives the contents towards the more dilated portion,

and thence they are forced into the œsophagus by abdominal pressure.

The same phenomena occur when a cat is given apomorphine

hypodermatically. First the upper circular muscles relax and become so

flaccid that the slightest movement of the abdomen changes the form

of the fundus. Then there are apparently irregular twitchings of the

fundus wall. Soon a deep constriction starts about three centimetres

below the cardia and, growing in strength, moves towards the pylorus.

When it reaches the transverse band the constriction tightens and holds

fast, while a wave of contraction sweeps over the antrum. Another

similar constriction follows. In the interval the transverse band

relaxes slightly, but tightens again when the second wave reaches

it. Perhaps a dozen such waves pass; then a firm contraction at the

beginning of the antrum completely divides the gastric cavity into

two parts. This same division of the stomach into two parts at the

transverse band is to be seen when mustard is given. Now, although

the waves are still running over the antrum, the whole preantral part

of the stomach is fully relaxed. A flattening of the diaphragm and a

quick jerk of the abdominal muscles, accompanied by the opening of the

cardia, now force the contents of the fundus into the œsophagus. As

the spasmodic contractions of the abdominal muscles are repeated, the

gastric wall again tightens around the contained food. Antiperistalsis

I have seen only once; then, while the cat was retching, a constriction

started at the pylorus and ran back, over the antrum, completely

obliterating the antral cavity.

It will be recalled that the principal difference between the

movements of the stomach and their effects as described by Beaumont,

and Hofmeister and Schütz on the one hand, and Rossbach, Roux and

Balthazard, and myself on the other hand, is that the former observed

constrictions completely dividing the stomach at the transverse band,

and the antrum then squeezing its contents into the intestines; whereas

the latter have seen the constrictions moving forward as narrowing

rings, but not separating the gastric cavity into two parts.

With the exception of peristalsis in the antrum, the gastric

movements at the beginning of emesis are almost exactly the same as

those Beaumont, and Hofmeister and Schütz, declare to be the normal

contractions of the stomach. Their observations were made, however,

when the organ was subjected to unnatural stimulation. In the excised

stomach, observed by Hofmeister and Schütz, not only were all nervous

connections severed, but likewise all flow of blood to the organ was

entirely stopped, and the cutting off of the blood supply is regarded

as one of the most powerful predisposing causes of peristaltic action.

The thermometer-tube used by Beaumont was an irritant to the stomach,

as he himself admits. “If the bulb of the thermometer,” he writes, “be

suffered to be drawn down to the pyloric extremity, and retained there

for a short time, or if the experiments be repeated too frequently, it

causes severe distress and a sensation like cramp, or spasm, which

ceases on withdrawing the tube, but leaves a sense of soreness and

tenderness at the pit of the stomach.” Moritz also noticed that a

rubber sound introduced into the human stomach proved to be a source

of irritation. It seems reasonable to suppose, therefore, that these

observers did not see the normal movements, but the actions resulting

from abnormal irritation.

THE EFFECT OF THE MOVEMENTS OF THE STOMACH ON THE FOOD

In my first observations on the active stomach a bulging of the

stomach-wall was to be seen in front of the passing waves. But as

food did not immediately appear in the intestine, and as, after the

pylorus relaxed, the gastric contents did not diminish rapidly enough

to allow the supposition that all of the food squeezed forward by the

waves was immediately forced through the pylorus, it was assumed that

a part, at least, of the food under pressure was forced back towards

the cardia through the constriction-ring. This inference was stated in

the preliminary notice of my work. Roux and Balthazard also observed

the passage of the undulations over the pyloric part, but state merely

that the function of the constrictions is the propulsion of food into

the intestine, without mentioning what must be regarded as a very

important function; namely, the mixing effect of the waves.

Most writers have agreed that the result of the active and passive

movements of the stomach is to force the contents hither and thither,

thus mixing them and the gastric juice together. Two observers,

Beaumont and Brinton, have attempted to explain the manner of the

mixing. Beaumont, after noting how the thermometer-tube, used by him to

indicate the gastric motions, was affected, describes the circulation

of the food as follows: “The bolus as it enters the cardia turns to the

left, passes the aperture, descends into the splenic extremity, and

follows the great curvature towards the pyloric end. It then returns,

in the course of the small curvature, makes its appearance again at

the aperture, in its descent into the great curvature, to perform

similar revolutions.” Brinton bases his theory of the circulation of

the food on an analogy between the movement of a constriction over the

stomach and the passage of a septum with a central perforation along

the interior of a cylinder full of liquid. The result in both cases,

he declares, must be a peripheral current of advance, and a central

current of return. Thus in the stomach there would be peripheral

currents from the cardia along the walls of the stomach to the

pylorus, where they would unite and run as an axial current back to the

cardia.

Certain _a priori_ objections may be urged against each of these

conclusions. In the first place Beaumont’s observations were made on

a subject having a gastric fistula, and the adhesions between the

stomach and the abdominal wall would prevent the fundus from acting

quite normally in relation to its contents. Beaumont’s conclusions,

furthermore, are based on the movements of a thermometer-tube

introduced through the fistula, and on the recognition of particles of

food which he had seen before as they passed the fistulous opening: the

first method, as has been shown, made the conditions in the stomach

more abnormal than they were previously; the second gave uncertain

knowledge of the course of the food when out of the observer’s sight.

Brinton’s hypothesis states the probable movements of fluid contents

acted on by a passing constriction. But it may be objected that the

conditions assumed by him do not exist in all parts of the stomach.

For not only is there no peristalsis visible in the fundus, but with

the usual food the fundus contents are not liquid. Moreover, the

constrictions at the beginning of the pyloric portion are very slight

and move slowly. The food in front of them is, accordingly, not under

much greater pressure than the food behind them. The axial current

which might result, therefore, could not be strong enough to go far

into the cardiac portion.

It is easily possible to test experimentally the validity of these

two theories by watching the action of pieces of food which throw a

black shadow in a dimly outlined stomach. For this purpose little

paste pellets of bismuth subnitrate, with starch enough to keep the

form, were given with the customary meal. These pellets, it was found,

did not break up in the stomach during the gastric digestion of soft

bread. Several times I have been fortunate in getting two of the little

balls in the axis of the stomach and about a centimetre apart. As the

constriction-wave approached them, both moved forward, but not so

rapidly as the wave. Now when the constriction overtook the first ball,

the ball moved backward through the constricted ring, in the direction

of least resistance. The wave then overtook the second ball, and it

also passed backward to join its fellow. At the approach of the next

wave they were both pushed forward once more, only to be again forced

backward, one at a time, through the narrow orifice. As the waves

recurred in their persistent rhythm, the balls were seen to be making

progress--an oscillating progress--towards the pylorus; for they went

forward each time a little farther than they retreated. This to-and-fro

movement of the pellets was much more marked in the antrum, where the

waves were deep, than in the middle region. On different occasions from

nine to twelve minutes have elapsed while the balls were passing from

where the waves first affected them to the pylorus; which means that

on the way they were moved back and forth by more than a half hundred

constrictions.

If the pylorus does not relax, it is evident that a wave approaching it

pushes the food into a blind, elastic pouch, the only exit from which

is through the advancing constricted ring. The constrictions are deeper

near the end of the antrum, and the rings are small; consequently,

the food is squirted back through them with considerable violence. As

has been noted, the pylorus opens less frequently for a while after a

solid piece of food comes to it. In such a case the slow driving waves

squeeze the hard morsel and the soft food about it up to the sphincter,

only to have the whole mass shoot back, sometimes half-way along the

antrum. Over and over again the process is repeated till the sphincter

at last opens and allows the more fluid parts to pass. Hofmeister and

Schütz, and Moritz have disclaimed any selective action of the pylorus,

and declare that solids are driven from the pylorus to the fundus by

antiperistalsis. The action of the pylorus which I have seen, however,

is more like that described by the earlier investigators; for during

digestion there was no antiperistalsis, and the sphincter, separating

the fluids from the solids, caused the solids to remain and undergo a

tireless rubbing. Frequently, when several of these balls have been

given at the same time, they have all been seen in the antrum after the

stomach was otherwise empty. Here they remain to be softened in time

by the juices, or to be forced through the pylorus later, for solids

do pass into the intestine. Thus when the teeth neglect their work the

stomach attempts to perform their function; the relative inefficiency

of the gastric method of grinding and its interference with the normal

gastric activities point an obvious hygienic moral.

During the process of digestion the food in the cardiac portion gives

no sign of currents. Balls which lie in the fundus immediately after

the food is ingested keep their relative positions until the cardiac

portion begins to contract, and then move very slowly towards the

antrum. Moreover, the food in the fundus of a cat has the same mushy

appearance when examined after gastric peristalsis had been active

for an hour and a half that it had when ingested. The contents of

the antrum, on the other hand, look quite different and have the

consistency of thick soup. The inactivity of the food in the fundus

can also be proved by feeding first five grams of bread and bismuth,

then five grams without bismuth, and finally five grams again with

bismuth in it. The stomach contents are thus arranged in two dark

layers along the curvatures, with a light layer between. Tracings made

on tissue paper show that ten minutes after peristalsis commenced the

stratification had entirely disappeared in the pyloric part, but that

an hour and twenty minutes thereafter the layers were still clearly

visible in the cardiac region.

The value of the circulation of the food, as described by Beaumont

and Brinton, lay in the supposition that the contents of the stomach

were thus brought near to the secreting gastric wall, and that the

gastric juice could thus more readily exert its action. Although my

observations do not support their theories of mixing currents running

throughout the stomach, they still show that the pyloric portion is

an admirable device for bringing all of the food under the influence

of the glandular secretions of that region. For, when a constriction

occurs, the secreting surface enclosed by the ring is brought close

around the food lying within the ring in the axis of the stomach.

As this constriction passes on, fresh areas of glandular tissue are

continuously pressed in around the narrow orifice. And also, as

the constriction passes on, a thin stream of gastric contents is

continuously forced back through the orifice, and thus past the mouths

of the glands. The result of this ingenious mechanism is that every

part of the secreting surface of the pyloric portion is brought near to

every bit of food, before the latter leaves the stomach, a half hundred

times or more, as evidence by the moving ball.

SALIVARY DIGESTION IN THE STOMACH

The absence of movement in the fundus would seem to give the food

during its stay there little opportunity to become mixed with the

gastric juices, and thus to undergo peptic digestion. The truth of

this supposition can easily be proved experimentally by feeding a

slightly alkaline meal, and later testing the chemical reaction of the

contents of various parts of the stomach. A cat which had been without

food for fifteen hours was given eighteen grams of mushy bread made

slightly alkaline with sodium carbonate. One hour and a half after

the cat had finished eating she was killed, and the stomach laid bare

by opening the abdomen. A very small hole was then made through the

wall in the fundus region, and another similar hole was made into

the antrum. By means of a glass pipette food was extracted first

from the periphery of the fundus; this food was slightly acid. The

cleaned pipette was then introduced two and a half centimetres into

the fundus contents, and the food thus extracted gave the original

alkaline reaction. Specimens of the liquid contents of the antral and

middle regions, taken from various depths, were all strongly acid.

A dog killed an hour and three-quarters after eating showed similar

differences between the reactions of the food in the fundus and the

food in the pyloric portion. So, as a matter of fact, the food does not

become acid at a uniform rate in all parts of the stomach, as would

be the case if Beaumont’s and Brinton’s theories of mixing currents

were true. Moreover, if the facts accorded with their notions, the

saliva, which ceases to act in the presence of more than 0.003 per

cent free hydrochloric acid, and is destroyed when the percentage

of acid proteids is large, would manifestly have its service as a

ferment limited to the relatively short time during which the stomach

contents, in the process of thorough mixing, were reaching that degree

of acidity. There is, however, no movement of food in the fundus, and

the alkaline food received from the œsophagus remains alkaline in this

region for a considerable period. The nutriment, therefore, if well

chewed and thus mixed with saliva, can undergo salivary digestion in

the fundus for a considerable period without interference by the acid

gastric juice.[32]

From all these observations the conclusion must be that the fundus

acts as a reservoir for the food, in which the digestion of sugars and

starches may take place; and that the pyloric portion with its simple

but marvellous peristaltic mechanism, by a single process, triturates

the food, brings it near to the active glands, stirs it thoroughly with

their secretions, and expels the products into the intestines.

THE INHIBITION OF STOMACH MOVEMENTS DURING EMOTION

Early in the research a marked unlikeness was noticed in the action

of the stomachs of male and female cats. The peristalsis seen with

only a few exceptions in female cats failed to appear in most of the

males, although both had received exactly the same treatment. Along

with this difference was a very striking difference in behaviour when

bound to the holder; the females would lie quiet, mewing occasionally,

but purring as soon as they were gently stroked. The males, on the

contrary, would fly into a violent rage, struggle to be loose from

their fastenings, bite at everything near their heads, cry loudly, and

resist all attempts to quiet them. On account of this difference only

female cats were used for some time, and the significance at first

attributed to the action of the males was almost forgotten when the

following incident recalled it and suggested that the excitement caused

the suspension of the stomach movements. On October 23, 1897, a male

cat was fed at 12.00, but was not placed on the holder till ninety

minutes later. The waves were passing at the rate of six a minute. The

cat fell into a rage and the waves suddenly stopped.

A few days later an observation on a female with kittens explained

the absence of gastric movements in the males. While the peristaltic

undulations were coursing regularly over the cat’s stomach, she

suddenly changed from her peaceful sleepiness, began to breathe

quickly, and struggled to get loose. As soon as the change took place,

the movements in the stomach entirely disappeared; the pyloric portion

relaxed and presented a smooth, rounded outline. I continued observing,

and stroked the cat reassuringly. In a moment she became quiet and

began to purr. As soon as this happened the movements commenced again

in the stomach; first a few constrictions were visible near the end of

the antrum, then a few near the sharp bend in the lesser curvature,

and finally the waves were running normally from their habitual

starting-place. By holding the cat’s mouth closed between the thumb and

last three fingers, and covering her nostrils with the index finger,

she could be kept from breathing. At the first sign of discomfort

the fingers were removed. This experiment was repeated a great many

times on different cats, and invariably the evidence of distress was

accompanied by a total suspension of the motor activities of the

stomach and a relaxation of the antral fibres.

No amount of kneading or compression of the abdomen with the fingers,

short of making the cat angry, would cause the waves to stop; so

that the cat’s movements, in themselves, were not the source of the

inhibition. And since expressions of strong feeling on the part of the

animal always accompanied cessation of the constriction-waves, the

inhibition was probably due to nervous influence. It has long been

common knowledge that violent emotions interfere with the digestive

process, but that the gastric motor activities should manifest such

extreme sensitiveness to nervous conditions is surprising.

SUMMARY

1. By mixing a harmless powder, subnitrate of bismuth, with the food,

the movements of the stomach can be seen by means of the Röntgen rays.

2. The stomach consists of two physiologically distinct parts: the

pyloric part and the fundus. Over the pyloric part, while food is

present, constriction-waves are seen continually coursing towards the

pylorus; the fundus is an active reservoir for the food and squeezes

out its contents gradually into the pyloric part.

3. The stomach is emptied by the formation, between the fundus and the

antrum, of a tube along which constrictions pass. The contents of the

fundus are pressed into the tube and the tube and antrum slowly cleared

of food by the waves of constriction.

4. The food in the pyloric portion is first pushed forward by the

running wave, and then by pressure of the stomach-wall is returned

through the ring of constriction; thus the food is thoroughly mixed

with gastric juice, and is forced by an oscillating progress to the

pylorus.

5. The food in the fundus is not moved by peristalsis, and consequently

it is not mixed with the gastric juice; salivary digestion can

therefore be carried on in this region for a considerable period

without being stopped by the acid gastric juice.

6. The pylorus does not open at the approach of every wave, but only at

irregular intervals. The arrival of a hard morsel causes the sphincter

to open less frequently than normally, thus materially interfering with

the passage of the already liquefied food.

7. Solid food remains in the antrum to be rubbed by the constrictions

until triturated, or to be softened by the gastric juice, or later it

may be forced into the intestine in the solid state.

8. The constriction-waves have, therefore, three functions: the mixing,

trituration, and expulsion of the food.

9. At the beginning of vomiting, the gastric cavity is separated into

two parts by a constriction at the entrance to the antrum; the cardiac

portion is relaxed, and the spasmodic contractions of the abdominal

muscles force the food through the opened cardia into the œsophagus.

10. The stomach movements are inhibited whenever the cat shows signs of

anxiety, rage, or distress.

THE MOVEMENTS OF THE INTESTINES STUDIED BY MEANS OF THE RÖNTGEN

RAYS[33]

BY W. B. CANNON

_From the Laboratory of Physiology in the Harvard Medical School_

Extracts from _American Journal of Physiology_, 1902

INTRODUCTION

The investigation of intestinal movements has been beset by the same

difficulties that characterised the investigation of the gastric

mechanism. Pathological subjects or animals subjected to the disturbing

action of drugs and anæsthetics and of serious operations have been the

only sources of our knowledge. A considerable difference of opinion as

to the nature of the normal movements in the intestines has resulted

from observations made under these necessary abnormal conditions. The

slowly advancing peristaltic wave and the _Pendelbewegung_, or swaying

movement, described by Ludwig, have been regarded as true physiological

processes. Concerning antiperistalsis and the swiftly running

vermicular contraction, observers are not so nearly in agreement.

The activity of the large intestine has been described as simply

peristalsis of a slower rate than that seen in the small intestine.

The best known of the intestinal movements is the normal peristaltic

wave. This wave is slow, having a rate of about two centimetres per

minute, is regular, and by most observers is said to move always in one

direction. The progress of the contraction, as suggested by Nothnagel’s

experiments, and as clearly stated by Mall and by Bayliss and Starling,

is dependent upon a local reflex. According to Mall, when an object

stimulates the mucosa there occurs above the point of stimulation a

constriction which forces the object downward; and as it moves downward

new regions immediately above the mass are by this reflex brought into

constriction, and thus the wave and its stimulus advance together. “At

the same time,” Mall states, “a sucking force, due to active dilatation

below the body, may have a tendency to drag it down.” In what manner

an active dilatation of the intestinal wall may occur so as to produce

a “sucking force” he does not make wholly clear. Bayliss and Starling,

in describing normal peristalsis in the intestine, state that the

contractions above the bolus increase until there is a strong tonic

constriction. This passes the bolus onward, and as it advances the ring

of constriction follows it. While the bolus is passing down, the gut

above it is traversed by waves running as far as the constricted ring.

These observers state the law of intestinal peristalsis thus: “Local

stimulation of the gut produces excitation above and inhibition below

the excited spot.”

The pendulum movements are characterised by a gentle swaying motion

of the coils, and are accompanied by rhythmical contractions of the

intestinal wall. They continue with undiminished force after paralysis

of the local nervous mechanism by nicotine or cocaine; they have been

called, therefore, myogenic or myodromic contractions. Observers have

described them variously as shortenings and narrowings of the gut,

rhythmically repeated at nearly the same intestinal circumference; as

alternating to-and-fro movements of the long axis without changes in

the lumen; as local or extensive periodic contractions and relaxations

mainly of the circular musculature; and as waves involving both

muscular coats of the intestine, and travelling normally from above

downward at a rapid rate (2 to 5 cm. per second). They have been

seen in the dog, and in the rabbit and cat. In the cat Bayliss and

Starling noticed that when the lumen of the gut was distended by a

rubber balloon, there appeared rhythmical contractions, which nearly

always were most marked at about the middle of the balloon; _i. e._,

the region of greatest tension. This form of constriction, which,

as my observation shows, is an indication of the manner in which

the rhythmical contraction acts in the cat’s intestine, Bayliss and

Starling seem to have regarded with slight attention, since it did not

accord with the law of peristalsis.

The swift vermicular wave may pass the whole length of the intestine

in about a minute. It is often seen just after death, as well as in

pathological states such as intestinal anæmia or hyperæmia, and when

the bowel contains gases and organic acids from decomposing food.

Starling is inclined to regard this type of intestinal activity as an

exaggeration of the rhythmic type; Mall, on the other hand, places

it in a class by itself, and declares that its service is to rid the

intestine rapidly of irritating substances. Nothnagel, who designates

this form of movement with the term _Rollbewegung_, thinks it is

transitional between a physiological and a pathological activity.

The existence of antiperistalsis has been so much questioned that

it will be considered in a special section of this paper, where my

observations may be conveniently introduced.

The common understanding of the manner in which food passes through the

intestinal canal is that the chyme ejected from the stomach is pressed

downward by a peristalsis, which passes slowly over a part or all of

the small intestine. The peristaltic waves of the colon are supposed

to constitute an independent group, similar to those of the small

intestine, but weaker and slower. Movements of the food other than the

uninterrupted advance have been mentioned by some observers. Starling

states that the effect of the pendulum movement is to mix the contents

of the intestine and bring them into intimate contact with the mucous

membrane. Grützner writes that he has been brought “by strange and

peculiar observations” to believe that the fluid contents of the small

intestine move irregularly forward, then forward and back, then perhaps

remain quiet for some time, only to pass backward for a long distance,

and finally to move forward steadily to the end. In this manner the

food is mixed and brought into contact with the absorbing walls. The

to-and-fro shiftings of the food Grützner ascribed to advancing and

retrograde contractions of the intestinal musculature, and he argued

that even circular constrictions must force the liquid contents away

in both directions. To support his contention, Grützner introduced

mercury into the intestine and observed it with the Röntgen rays. After

noting a backward and forward movement of the mercury he dismissed the

method, saying, “Many a flash must come from the Röntgen tube before

the _normal_ movement of the intestinal contents is made entirely clear

by this method.”

The following account is a summary of many repeated observations on

different animals, and is a contribution to a clear understanding of

the normal movements of the intestines and their contents.

THE MOVEMENTS OF THE SMALL INTESTINE

When the food has been distributed through the intestine so as to

present the appearance shown in Figure 1, a noticeable feature in most

or all of the loops is the total absence of movement. If the animal

remains quiet, however, only a few moments elapse before peculiar

motions appear in one or another of the loops, or perhaps in several,

and last for some time. These motions consist in a sudden division

of one of the long, narrow masses of food into many little segments

of nearly equal size; then these segments are again suddenly divided

and the neighbouring halves unite to make new segments, and so on, in

a manner to be more fully described. I have called this process the

rhythmic segmentation of the intestinal contents. Further observation

reveals peristalsis here and there, and under certain circumstances the

typical swaying movements may be seen. All these phenomena are now to

be considered in detail.

[Illustration:

FIGURE 1.--Appearance of food in the intestines 5¾ hours after eating.

This and other radiographs reduced two-thirds.]

[Illustration:

FIGURE 2.--Diagram representing the process of rhythmic segmentation.

Lines 1, 2, 3, 4 indicate the sequence of appearances in the loop.

The dotted lines mark the regions of division. The arrows show the

relation of the particles to the segments they subsequently form.]

_Rhythmic segmentation of the intestinal contents._--This is by far the

most common and the most interesting mechanical process to be seen in

the small intestine. The nature of the process may best be understood

by referring to the diagram in Figure 2. A string-like mass of food

is seen lying quietly in one of the intestinal loops (line 1, Fig.

2). Suddenly an undefined activity appears in the mass, and a moment

later constrictions at regular intervals along its length cut it into

little ovoid pieces. The solid string is thus quickly transformed,

by a simultaneous sectioning, into a series of uniform segments. A

moment later each of these segments is divided into two particles,

and immediately after the division neighbouring particles (as _a_

and _b_, line 2, Fig. 2) rush together, often with the rapidity of

flying shuttles, and merge to form new segments (as _c_, line 3, Fig.

2). The next moment these new segments are divided, and neighbouring

particles unite to make a third series, and so on. At the time of the

second segmentation (line 3, Fig. 2) the end particles are left small.

Observation shows that these small pieces are not redivided. The end

piece at A simply varies in size with each division; at one moment it

is left small, at the next moment it is full size from the addition

of a part of the nearest segment, and a moment later is the small bit

left after another division. The end piece at B (probably the rear

of the mass) shoots away when the end mass is divided, and is swept

back at each reunion to make the large end mass again, only to be

shot away and swept onward with each recurrence of the constrictions.

Thus the process of repeated segmentation continues, with the little

particles flitting towards each other and the larger segments shifting

to and fro, commonly for more than half an hour without cessation.

From the beginning to the end of a period of segmentation the food

is seen to have changed its position in the abdomen to only a slight

extent; whether this change is a passing of the food along the loop,

or a movement of the loop itself, it is impossible to tell from the

shadows on the screen. The change of position, however, is much less

conspicuous than the lively division and redivision which the mass

suffers so many times from the busy, shifting constrictions.

From this typical form of rhythmic segmentation there are several

variations. Sometimes, and especially when the mass of food is thick,

the constrictions do not make complete divisions and are so far apart

that the intermediate portions are relatively large. Moreover, the

constrictions do not take place in the middle of each portion, but

near one end; thus each portion is constricted, not into halves,

but into thirds. If a little pointer is placed at the middle of a

segment, when the segments are completely divided into halves, in a few

seconds the pointer will be in the middle of the clear space between

two segments; but in a few seconds more the first phase will return

and the pointer will again be indicating a segment,--two operations

intervene between similar phases. When, however, the portions are

constricted into thirds, the indicator shows it, since three operations

intervene between similar phases. The manner of these changes is made

clearer by reference to the diagram in Figure 3. That each portion is

constricted into three pieces is proved also by watching the gradual

reduction of the portion at the left end of line 1 through lines 2

and 3, and also in the gradual formation of a full-sized portion at

the right end of lines 2, 3, and 4. When food undergoing this process

is watched, it appears to be affected by a series of constrictions,

each of which starts at one end of the mass and marches through to the

other end, leaving its impress at short intervals along the length. The

progression of the dotted lines from right to left in _a_, _b_, _c_,

and _d_, etc., Fig. 3, gives a notion of these advancing constrictions.

Another variation of the segmentation is shown in Figure 4. In this

type there are evidently divisions and subdivisions, _i.e._, one more

operation between the appearance and the reappearance of the same phase

than is present in the simple division of the small segments in a long

string of food (Fig. 2). This form of segmentation is fairly typical

for the constrictions seen in food advancing through the intestine.

Sometimes the divisions occur in the middle of a long string of food

and leave the ends wholly unaffected.

[Illustration:

FIGURE 3.--Diagram showing the relations of the portions when they are

constricted into three pieces. The dotted lines indicate regions of

constriction; the arrows indicate the relationship of the pieces to

the portions they subsequently form.]

A remarkable feature in the segmentation of the food is the rapidity

with which the changes take place. The simplest way of estimating the

rate of division is to count, not the number of times the partition of

the food recurs in the same place, but the number of different sets of

segments observed in a given period. Thus in Figure 4 the appearances

of lines 1, 2, 3, 4, etc., would be counted, and not merely lines 1,

4, etc. Repeated observations on different animals have shown that

the most common rate of division in long, thin chains of food varies

between twenty-eight and thirty times in a minute; _i. e._, there is

a change from one set of segments to another set every two seconds,

and a return of the same phase every four seconds. In some cases the

rate is as low as twenty-three times per minute. The larger masses seem

to be associated with a slower segmentation; the operations indicated

in Figure 3, for example, occurred from eighteen to twenty-one times

in a minute, so that the same phase reappeared only once in eight or

nine seconds. The segmentation frequently continues for more than half

an hour; in one instance it was seen to persist with only three short

periods of inactivity for two hours and twenty-two minutes. At the rate

of thirty segmentations per minute it is clear that a slender string

of food may commonly undergo division into small particles more than a

thousand times while scarcely changing its position in the intestine.

I have seen once, in a cat only lightly etherised, the exterior of an

intestine which was dividing the food as above described. An hour and

a half after a meal of salmon the anæsthetic was given, the abdomen

opened, and the flaps raised so as to form walls. Warm salt solution

was then poured into the abdominal cavity, and the floating coils left

covered with the transparent omentum. The gastric peristaltic waves

were running regularly; on the intestine there were visible at various

places during the period of observation regions of constriction which

had the appearance shown in Figure 3, except that the rings were

relatively nearer together. New rings of constriction took place on the

same side of all the bulging parts at the margin of the constricted

portion (_cf._ dotted lines, Fig. 3). As new rings occurred the old

relaxed, but apparently with tardiness, for the contents gurgled as

if forced through the narrowed lumen. The constrictions recurred

irregularly and at much longer intervals than in the normal animal. The

contracted rings were pale and bloodless.

The effect of the process of rhythmic segmentation proves it an

admirable mechanism. The food over and over again is brought into

closest contact with the intestinal walls by the swift kneading

movement of the muscles. Thereby not only is the undigested food

intimately mixed with the digestive juices, but the digested food is

thoroughly exposed to the organs of absorption. Mall has shown that

contraction of the intestinal wall has the effect of pumping the blood

from the submucous venous plexus into the radicles of the superior

mesenteric vein, and thus materially aids the intestinal circulation.

Moreover, lacteals loaded with fat will in a few moments become empty

unless the intestine is slit lengthwise, so that the muscles cannot

exert compression. The rhythmic constrictions, therefore, both

propel the blood in the portal circulation and act like a heart in

promoting the flow of lymph in the lacteals. This single movement with

its several results is an excellent example of bodily economy; the

repeated constrictions, as already shown, thoroughly churn the food and

digestive fluids together, and also plunge the absorbing mucosa into

the very midst of the food masses: but not only are the processes of

digestion and absorption favoured by these movements; they also, by

compression of the veins and lacteals of the intestinal wall, serve

to deport through blood and lymph channels the digested and absorbed

material.

_Peristalsis._[34]--The phenomena of peristalsis and segmentation are

usually combined in some manner while the food passes through the small

intestine. Peristalsis is observed normally in two forms: as a slow

advancing of the food for a short distance in a coil, and as a rapid

movement sweeping the food without pause through several turns of the

gut. The latter form is frequently seen when the food is carried on

from the duodenum; and it may readily be produced in other parts of the

small intestine by giving an enema of soapsuds.

When a mass of food has been subjected for some time to the segmenting

activity of the intestine, the separate segments, instead of being

again divided, may suddenly begin to move slowly along the loop in

which they lie. That this movement is not a swinging of the coil as

a whole, but a peristaltic advance of separate rings of its circular

musculature, is made probable by the fact that the succeeding segments

follow along the same path their predecessors have taken. The advance

of the little pieces may continue for seven or eight centimetres,

when finally the front piece stops or meets other food. Then all the

succeeding pieces are swept one by one into the accumulating mass,

which at last lies stretched along the intestine, a solid string

manifesting no sign of commotion.

[Illustration:

FIGURE 4.--Diagram showing combined peristalsis and segmentation.]

Another form of slow peristalsis is frequently observed when the food

is pushed forward, not in small divisions, but as a large lump. The

relatively long string of food is first crowded into an ovoid form as

the forward movement begins, and as it is collecting thus, it seems

at the last to be suddenly formed into a more rounded ball, as if the

mass were pulled or pushed together at the two ends. The next moment

it is indented in the middle by a circular constriction (as shown in

Fig. 4, line 2), which spreads it in both directions along the loop.

The trailing portion (_a_) is next cut in two, and the severed part

sometimes flies back over its course about a centimetre. Now the whole

mass is swept together again and slightly forward as shown in line 4,

Fig. 4, and the segmenting process is repeated. At stage 3, Fig. 4,

a constriction sometimes appears around the middle of the advanced

portion (_b_). Thus, with many halts and interruptions, the food slowly

advances.

A slight variation of the movement just described is observed when the

amount of food is greater and extends farther along the intestine.

Under such circumstances, as the mass moves forward, constrictions

appear just in front of the rear end, which separate it from the main

body, and cause it to shoot backward sometimes through the distance of

a centimetre. The main body meanwhile is not disturbed. No sooner has

the rear section been shot away than it is swept forward again into

union with the rest of the food, and the whole mass then advances until

another interfering constriction repeats the process.

_Rhythmic segmentation and the pendulum movement._--There is little

doubt that the segmentation of the food which I have seen is due

to an activity of the intestinal musculature similar to that which

causes the so-called pendulum movement. This activity, as already

noted, is rhythmic, and, although accounts differ, analytical methods

prove that it involves both the longitudinal and the circular layers

of muscle. Observations of the effect of the rhythmic contractions

upon the food show that the action of the circular fibres is most

prominent. It is probable, however, that the longitudinal fibres also

play an important part in the process of segmentation. Examination

of Figure 2 makes clear that in line 2 the regions of constriction

appear between the regions of constriction in line 3; before _c_ can

be formed, therefore, the constriction between _a_ and _b_ must relax.

Contraction of the longitudinal fibres between two segments would help

to enlarge the constricted lumen of the gut. It seems probable that, as

the constrictions on either side of _c_ occur, the longitudinal fibres

between them contract; almost simultaneously the constriction between

_a_ and _b_ relaxes, and the two particles are thus brought swiftly

together. A similar process naturally would take place for each of

the shifting segments. Thus the function of the longitudinal muscles

would be to contract between new rings of constriction and thereby aid

in relaxing the former ring between them. During my one observation

of the segmenting process, as seen on the surface of the intestine,

I could not be sure that the distance between neighbouring segments

was shortened as the constriction relaxed; that activity of the

longitudinal fibres is present, however, is indicated by observations

of Raiser on the intestines of the rabbit and the cat. Raiser observed

the outer surface of the coils, and describes the normal movement

as an alternate contraction and relaxation of single divisions of

the longitudinal fibres; he notes that these short divisions shift.

But whether they shift in alternation with the shifting circular

constrictions, as seems probable, is an interesting point not yet

determined.

[Illustration: FIGURE 5.--Tracing showing segmentation of chyme in the

duodenum. This and other tracings reduced two-thirds.]

Bayliss and Starling state that the swaying pendulum movements are

essentially due to peristaltic waves recurring in the same place and

running rapidly downward. This form of the movements I have seen only

once. At this time about 90 c.c. of soapy water had been injected.

This procedure has the effect of exaggerating in every particular the

movements of the small intestine. In this instance a broad constriction

appeared about the middle of a long string of food and persisted there

while it spread down the gut. As the contraction spread, the gut swayed

slowly to and fro before it. Then there was a relaxation, followed by

a recurrence of the constriction in the same place, a spreading of the

contraction, and a swinging of the loop just as before. This phenomenon

was repeated again and again, till finally the string was divided and

the forward piece pushed through a tortuous course to the colon.

_The course of the food in the small intestine._--Chyme is not forced

from the stomach by every wave that passes over the antrum, but only

at intervals. When the pylorus relaxes, the food, moved towards the

pylorus under considerable pressure, is squirted along the duodenum

for two centimetres or more. Careful watching of this food shows that

usually it lies for some time in the curve of the duodenum until

additions have been made to it from the stomach, and a long, thin

string of food is formed. While it is resting in this place it is

exposed to the outpouring of the bile and pancreatic juices. All at

once the string becomes segmented (see Fig. 5) and the process of

rhythmic segmentation continues several minutes, thoroughly mixing

the intestinal digestive juices with the chyme. In this region the

alternate positions of the segments are sometimes far apart, and the

to-and-fro movements of the particles may be a relatively extensive

and very energetic swinging. Finally the little segments unite into

a single mass, or form in groups, and begin to move forward. The

peristalsis here, as already mentioned, is much more rapid than the

normal peristalsis elsewhere in the small intestine. The masses, once

started, go flying along, turning curves, whisking hither and thither

in the loops, moving swiftly and continuously forward. After passing on

in this rapid manner for some distance the food is collected in thicker

and longer strings, resembling the strings seen characteristically in

the other loops. Towards the end of digestion the small masses shot

out from the stomach, after a few segmentations, may move on in the

rapid course without being accumulated in a larger mass until the swift

movement ceases.

During the first stages of digestion in the cat’s small intestine the

food usually lies chiefly on the right side of the abdomen; during the

last stages the loops on the left side contain the greater amount of

food. In these loops the food remains sometimes for an hour or more

with no sign of movement. All at once a mass begins to show irregular

depressions and elevations along its length, and then suddenly it is

divided, at first partially, later completely, into many little equal

parts, and these repeatedly undergo division and reunion, division

and reunion, over and over again, in the manner described above as

rhythmic segmentation. After a varying length of time the activity

wanes and the little segments are carried forward individually and

later brought together, or join and move on as a single body, or they

may reunite and lie quietly for some time without further change. Thus

by a combined process of kneading and peristaltic advance the food is

brought to the ileocæcal valve to enter the large intestine. Records

from ten different animals show that salmon does not appear in the

small intestine until an hour or an hour and a half after the food is

eaten. Inasmuch as five or six hours elapse after eating before this

food begins to be seen in the colon, it is evident that the chyme takes

four to five hours to pass the length of the small intestine. It is

interesting to note that the operations are considerably shortened if

the meal has consisted of bread and milk.

THE COMPETENCE OF THE ILEOCÆCAL VALVE

The ileocæcal valve in the cat is situated three or four centimetres

from the blind end of the cæcum. Its position is usually marked in

shadows of the food in the colon by a slight indentation, towards which

masses about to enter the colon are ordinarily directed from a point

somewhat distant in the small intestine (see Fig. 6).

Regarding the competence of the ileocæcal valve many observations

have been made. Grützner has reviewed the evidence bearing on the

question and concludes that the valve is not competent, least of all

for liquids. He declares that as soon as liquids or thin fluid masses

appear in the upper part of the colon they pass in many instances into

the small intestine the moment that the pressure on the colon side

rises slightly. If the colon contains a solid or a thick, mushy mass,

the passage towards the small intestine is scarcely possible, because

every increase of pressure in the large intestine must force the two

lips of the valve together and close it.

The importance of the competence of the ileocæcal valve under normal

conditions cannot be appreciated until the function of the first part

of the colon is considered. In order that this part of the intestinal

mechanism may perform its service, the competence of the valve for the

food which enters the colon from the ileum should be perfect. As a

matter of fact, such is the case. Not only does the activity of the

colon prove this statement, but the failure of every attempt to drive

the food in the colon back through the valve into the ileum confirms

the proof. Again and again I have tried, by manipulation through the

abdominal wall, to press the normal contents of the colon downward with

sufficient force to cause them to return to the small intestine, but

without success. The valve held perfectly.

THE MOVEMENTS OF THE LARGE INTESTINE

When the large intestine is full, palpation through the abdominal wall

demonstrates that the material in the lower descending colon and in

the sigmoid flexure is usually composed of hard, incompressible lumps,

while that in the ascending and transverse colon and the cæcum is

soft, permitting the walls of the gut to be easily pushed together.

The condition of the contents in these two regions seems to indicate

a rough division of the large intestine into two parts, and the

mechanical activities of these two parts verify the differentiation. In

the descending colon the material is very slowly advanced by rings of

tonic constrictions (see Fig. 7); in the ascending and transverse colon

and in the cæcum by far the most common movement is an antiperistalsis.

_Antiperistalsis in the colon._--The colon of cats which have been

without food for a day usually contains enough gas to make the position

of the gut distinguishable with the fluorescent screen (see Fig. 1).

The first food to enter the colon from the small intestine is carried

by antiperistaltic waves into the cæcum (Fig. 1), and all new food as

it enters is also affected by these waves. Thus the contents of the

colon, instead of being driven immediately toward the rectum by slow

peristalsis, as is the general opinion, are first repeatedly pushed

toward the cæcum by an antiperistaltic action.

These antiperistaltic waves follow one after another like the

peristaltic waves of the stomach (see Figs. 5, 6, and 10). They begin

either on the more advanced portion of the food in the colon (when only

a small amount is present), or at the nearest tonic constriction, which

is usually at the turn between the transverse and descending colon

(Figs. 7 and 8.) The waves rarely run continuously for a long time.

When the colon is full, it is usually quiet. The first sign of activity

is an irregular undulation of the walls, then very faint constrictions

passing along the gut towards the cæcum. These constrictions may

first appear only on the ascending colon. As they continue coursing

over the intestine they become deeper and deeper, until there is a

marked bulging between successive constrictions. When the waves have

thus become more prominent, they are seen to start near the end of

the transverse colon and pass without interruption to the end of the

cæcum. After these deepest waves have been running for a few minutes

the indentations grow gradually less marked, until at last they are so

faint as to be hardly discernible. The final waves are sometimes to be

observed only at the end of the transverse colon.

Such a period of antiperistalsis lasts from two to eight minutes,

with an average duration of four or five minutes. The periods recur

at varying lengths of time; in one instance a period began at 1.38

P.M. and was repeated at 2.06, 2.34, 2.55, 3.15, and at 3.36, when

the observation ceased; in another instance a period began at 2.43

P.M., and was repeated at 2.57 and at intervals of from ten to fifteen

minutes thereafter while the animal was being watched. The waves have

nearly the same rate of recurrence as those in the stomach; about five

and a half waves pass a given point in a minute, _i. e._, eleven waves

in two minutes. This rate has proved fairly constant in different cats

and at different stages in the process of digestion; in one case,

however, the waves passed at the rate of nine in two minutes.

The stimulating effect of rectal injections on the movements of the

small intestine has already been noted. Enemata have also pronounced

stimulating action on the antiperistalsis of the colon. Usually the

almost immediate result of a rectal injection of warm water is the

appearance of deep antiperistaltic waves, which often continue running

for a long period. In one case, after an injection of 50 c.c. of warm

water, the waves followed one another with monotonous regularity during

an observation lasting an hour and twenty minutes. The manner in which

this antiperistaltic mechanism affects nutrient enemata introduced into

the bowel will be discussed in the section devoted to the question of

antiperistalsis.

These constrictions passing backward over the colon do not force

the normal contents back through the valve into the small intestine

again. I have seen hundreds of such constrictions, and only twice have

there been exceptions to this rule,--once under normal conditions,

when a small mass slipped back into the ileum, and at another time

when a large amount of water had been introduced into the colon. The

importance of the competence of the ileocæcal valve is now apparent;

indeed, antiperistalsis in the colon gives new meaning and value to

the location of a valve at the opening of the ileum. For, inasmuch

as the valve is normally competent, the constrictions repeatedly

coursing towards it force the food before them into a blind sac. The

effect on the food must be the same as the effect seen in the stomach

when the pylorus remains closed before the advancing waves. The food

is pressed forward by the approach of each constriction; but since

it cannot go onward in the blind sac, and is, moreover, subjected to

increasing pressure as the constriction comes nearer, it is forced

into the only way of escape, _i. e._, away from the cæcum through

the advancing constricted ring. About twenty-five waves affect every

particle of food in the colon in this manner during each normal period

of antiperistalsis. The result must be again a thorough mixing of the

contents and a bringing of these contents into close contact with the

absorbing wall--a process which has already been variously repeated

many times in the stomach and in the small intestine.

Two other movements have been observed in the ascending colon, but

they are rare appearances. The first of these was a serial sectioning

of the contents noticed in an animal given castor oil with the food.

A constriction separated a small segment in the cæcum; another

constriction then cut off a segment just above the first, and with the

disappearance of the first constriction the two separated segments

united. A third segmentation took place above the second, and the

changes occurred again. Thus the whole mass was sectioned from one

end to the other; and no sooner was that finished than the process

began again and was repeated several times. A slight modification of

this movement was observed in a colon containing very little food. The

mass was pressed and partially segmented in the manner characteristic

of the small intestine, and was thus again and again spread along

the ascending colon, and each time swept back into a rounded form

by antiperistalsis. The second of the two movements mentioned above

consisted in a gentle kneading of the contents. This was caused by

broad constrictions appearing, relaxing, appearing, relaxing, over

and over again, in the same place. When several of these regions were

active at the same time, they gave the food in the colon the appearance

of a restless undulatory mass. Once a constriction occurred and

remained permanently in one place, while the bulging parts on either

side of it pulsated alternately, at the rate of about eighteen times

in a minute, with the regularity of the heart-beat. Although these

phenomena are somewhat striking, they are not usual, and are in no way

so important as the antiperistalsis.

_The changes when food enters the colon._--The passage of food through

the ileocæcal valve seems to stimulate the colon to activity. As food

is nearing the ileocæcal valve the large intestine is usually quiet and

relaxed (Fig. 6, 4.00), though occasionally indefinite movements are

to be observed; and sometimes just before the food reaches the end of

the ileum the circular fibres of the colon in the region of the valve

contract strongly, so that a deep indentation is present there. The

indentation may persist several minutes; it disappears as the muscles

relax just previous to the entrance of the food. The food is moved

slowly along the ileum and is pushed through the valve into the colon.

The moment it has entered a strong contraction takes place all along

the cæcum and the beginning of the ascending colon, pressing some of

the food onward, and a moment later deep antiperistaltic waves (Fig. 6,

4.03) sweep down from the transverse colon and continue running until

the cæcum is again normally full, _i. e._, for two or three minutes.

[Illustration:

FIGURE 6.--Tracings showing changes when food enters the colon and

also the first tonic constriction. 4.00, the colon relaxed as food

approaches in the ileum. 4.03, the colon contracted and traversed by

antiperistaltic waves after the food has entered.]

_The appearance of tonic constrictions._--It has already been noted

that as the food accumulates in the ascending colon it is at first

confined to this region by antiperistaltic waves. With further

accessions, however, the contents naturally must be pressed more and

more into the transverse and descending colon. In the early stages of

this accumulation, while the food lies chiefly in the ascending colon,

the only activity of the muscular walls is the antiperistalsis. As the

contents extend along the intestine a deep constriction appears near

the advancing end and nearly separates a globular mass from the main

body of the food (Fig. 6). The contents of the large intestine progress

farther and farther from the cæcum; meanwhile new tonic constrictions

appear which separate the contents into a series of globular masses.

And as the number of these divisions increases they take a position

farther from the cæcum, so that they are present chiefly in the

descending colon (Fig. 7). Raiser has recorded a similar appearance

in the terminal portion of the rabbit’s colon, in which deep circular

constrictions separate the scybalous masses. He maintains that these

masses are pushed onward by the constrictions. Comparing tracings

made at rather long intervals (forty-five minutes), I found that the

rings disappear from the transverse colon, and then are present with

the waste material in the descending colon. Thus in the cat also

these rings, which seem with short observation to be remaining in one

position, are in reality moving slowly away from the cæcum, pushing

the hardening contents before them. The contents at this stage are no

longer fluid, and consequently they must offer considerable resistance

to a force pushing them through the colon. It is an advantage to have

this pultaceous substance propelled in divisions rather than in a

uniformly cylindrical mass, since the fibres along the length of the

mass are thereby rendered effective. Such are the functions of the

persistent rings; they form the waste matter into globular masses at

the end of the transverse colon and slowly push these masses onward.

[Illustration:

FIGURE 7.--Radiograph showing the region of tonic constrictions

(descending colon) and the region of antiperistalsis (transverse and

ascending colon).]

In the transverse colon, which is free from the slowly moving rings,

the antiperistaltic waves have full sway. In the region of the

tonic rings an infrequent or even a slowly periodic relaxation and

contraction are often to be observed. These changes seem to take place

in all the rings at about the same time. Once I saw antiperistaltic

waves running over the uppermost of four segments, but since the rings

on either side of the segment held tightly, the waves had merely the

effect of churning the material of the segment and did not move it

onward. Inasmuch as the material in these segments at first is soft, so

that the segments are easily compressible, while the fæcal masses which

are the final result are relatively hard and dry, it follows that even

within the confines of these persistent rings some absorption is taking

place.

DEFECATION

The process of clearing the colon is a process of repeated reduction

of the amount of material present. Figure 8 (3.11) is a radiograph

showing the food in the colon at 3.11 P.M. About 3.25, with a slow,

sweeping movement, the gut swung around so that the ascending colon was

lying in the position of the last half of the transverse colon, and the

transverse colon had taken the position of the descending part (Fig.

8, 3.25). At the same time the tonic constrictions disappeared and

were replaced by a strong, broad contraction of the circular muscle,

tapering the contents off on either side in two cones. The region of

strongest contraction was apparently drawn downward with the rest of

the gut by a shortening of the descending colon. As the intestine

swung around, more material was forced into the rectum, and when the

swinging of the intestine stopped, the constriction which divided

the lumen passed slowly downward, and with the aid of the muscles

surrounding the abdominal cavity, pushed the separated mass out of

the canal.[35] After the terminal mass had thus been pushed out, the

colon with the remainder of its contents returned to nearly its former

position (Fig. 8, 3.46). About two hours afterward this remnant had

been spread throughout the length of the large intestine by means of

the slowly moving rings. Figure 7 is a radiograph of the same colon

pictured in Figure 8; the radiograph was taken at 11.50 A.M., and at

12.15 P.M. the material in the lower descending colon was forced out in

the manner above described. Within three hours the remaining portion

had been spread into the evacuated region, as shown in Figure 8, 3.11.

The manner in which the material is spread from the region of the

antiperistaltic waves into the region of the slowly advancing rings

presents a problem. During normal living new food constantly arriving

in the colon must force the old contents forward just as the later

parts of a meal force forward the earlier parts; there is no doubt,

however, that most of the contents of the cæcum and the ascending colon

may be passed onward even during starvation. The emptying of these

regions, according to my observations, is never complete; for after

considerable time has elapsed and the large intestine is cleared and

dilated with gas, some substance is still to be detected in the cæcum

and clinging to the walls of the ascending colon. The only activities

manifested here are the antiperistaltic waves and the strong tonic

contraction of the whole circular musculature shown in Figure 6. It is

clear that the latter activity would serve to press into the transverse

colon a considerable portion of the contents of the ascending colon,

and the remnant seen clinging to the walls would be the part not thus

pressed forward.

[Illustration:

3.11 3.25 3.46

FIGURE 8.--Two radiographs and a tracing showing the changes taking

place in defecation. 3.11, material in the colon. 3.25, colon carried

downward and terminal mass separated. 3.46, after defecation, when the

colon returns to former position. Defecation occurred at 3.27.]

Twice I have seen appearances which might account for the emptying of

the first portion of the large intestine in a more thorough manner

than that above described. At one time, without apparent stimulation,

strong tonic contraction occurred along the entire length of the

ascending colon, which forced the contents almost wholly into the

transverse portion. This action seemed merely an exaggerated form of

that observable after food passes the ileocæcal valve (see Fig. 6). At

another time, after a mass of food had passed through the ileocæcal

valve, after the ascending colon had contracted generally and the

antiperistaltic waves had coursed over it in the usual manner, a deep

constriction appeared at the valve and ran upward without relaxation

nearly the length of the ascending colon, pushing the contents before

it. For an instant the wave paused; then the constriction relaxed and

the food returned towards the cæcum. These observations indicate that

either a general contraction of the wall of the large intestine or a

true peristalsis may be effective in pressing waste matter from the

region where antiperistalsis is the usual activity into the region

where the slowly advancing rings may carry it on to evacuation (see

Fig. 7).

THE QUESTION OF ANTIPERISTALSIS

In 1894 Grützner published an observation and made an assumption about

which there has since been much controversy. He maintained that when

normal salt solution, holding in suspension hair, powdered charcoal, or

starch grains, is injected into the rectum, it is carried upward into

the small intestine and may even enter the stomach. These experiments

have been repeated by several observers. Some have confirmed Grützner’s

results; others have failed, after using most careful methods, to

find any evidence of the passage of the injected material back to the

stomach, and they have declared that the apparent success was due to

carelessly allowing the food of the animal to become contaminated with

the test materials, so that these were introduced into the stomach by

way of the mouth. That antiperistalsis does not occur in the small

intestine seems to be proved by Mall’s experiment of reversing a

portion, sewing it in place, and then finding that the food does not

pass the reversed region, but collects at the upper end. Sabbatani

and Fasola reversed stretches of small intestine of varying length,

and found that the reversed portions allowed fluids to pass, but that

the persistence of the physiological direction of movement caused an

accumulation of undigested food in the region of the upper suture.

However a portion of the intestine lay in relation to the rest, it

always manifested the normal peristalsis. Many other observers working

directly on the intestine confirm this testimony and state that the

progress of the constriction-rings is always downward, and that

antiperistalsis is not physiological. In 1898, however, Grützner took

his stand again in favour of a backward movement in the intestines,

and in a somewhat metaphysical manner argued that peristalsis and

antiperistalsis belong to each other just as relaxation of muscle is

related to contraction. He assumed that as the contents are advanced

by slow peristalsis, so are they returned by a similar movement in

the opposite direction, and he mentions several pathological cases

(fistula of intestine) to substantiate the assumption.

By means of the X-rays it is possible to see just what takes place when

a fluid is injected into the rectum. For the purpose of determining

how nutrient enemata are received and acted upon in the intestines,

I have introduced thin, fluid masses in large and small amounts, and

thick, mushy masses in large and small amounts, in different animals.

The enemata consisted of 100 c.c. of milk, one egg, ten to fifteen

grams of bismuth subnitrate, and two grams of starch to hold the

bismuth powder in suspension. To make the thick enema all these were

stirred together and boiled to a soft mush; to make the thin enema

all the parts were boiled together except the egg, which was added

after the boiled portion was cooled. The small amount injected was 25

c.c.; the large amount almost 90 c.c., about the capacity of the large

intestine when removed from the body. The animals were given first a

cleansing injection, and after this was effective the nutrient material

was introduced. In order to make sure of the observation, a control

radiograph was first taken to show no bismuth food present, and other

radiographs taken at varying intervals after the injection to record

the course the food was following.

[Illustration:

1.50 2.15 3.00

FIGURE 9.—- Radiographs showing that after a large nutrient enema

(about 90 c.c.) has been given the food is forced more and more from

the large into the small intestine. The enema was introduced at about

1.40 P.M. At 3.00 segmentation was occurring in many loops.]

These experiments show that when small amounts of nutrient fluid are

introduced they lie first in the descending colon. In every instance

antiperistaltic waves are set going by the injection, and the material

is thereby carried to the cæcum. When large amounts are injected they

stop for a moment in the region between the transverse and descending

colon, as if a constriction existed there. Then a considerable amount

of the fluid passes the point, and antiperistaltic waves carry it

to the cæcum. In any case the repeated passing of the waves seems

to have the effect of promoting absorption, for in the region where

these waves continue running, the shadows become gradually more dim,

and finally the bismuth appears to be only on the intestinal walls;

in other regions, _e. g._ in the descending colon, the shadows retain

their original intensity. Small injections have never in my experience

been forced even in part into the small intestine; but with the larger

amounts, whether fluid or mushy, the radiographs show many coils of the

small intestine containing the bismuth food.

The passage of the injected material beyond the ileocæcal valve is

probably due entirely to antiperistalsis in the colon,--a factor

unknown to both Grützner and his opponents. The valve, which is

thoroughly competent for food coming normally from the small intestine

into the large, is curiously incompetent for a substance, even of the

consistency of thick cream, introduced in large amount by rectum. When

the valve first permits the food to enter the ileum, the fluid pours

through and appears suddenly as a winding mass occupying several loops

of the intestine (Fig. 9, 1.50, about ten minutes after the injection).

The mass is continuous from the valve to the other end; antiperistalsis

is therefore not visible in the small intestine under the circumstances

of this experiment. The antiperistaltic waves of the colon, however,

continue running; the transverse and ascending colon are thus almost

emptied, and the small intestine more and more filled with food (Fig.

9, 2.15 and 3.00). After a short time the typical segmenting movements

can be seen in the loops, busily separating the food into small masses,

and over and over again dividing and redividing them.

I have never seen food material pass back from the colon so far as the

stomach; but once, about ten minutes after an injection of 100 c.c. of

warm water, the cat retched and vomited a clear fluid resembling mixed

water and mucus. In the fluid were two intestinal worms still alive.

The importance of the mechanism by which nutrient enemata are passed

backward in the intestine is evident. In the colon the nutrient

material is worked over by the antiperistaltic waves, intimately

mixed with whatever digestive juices may be present, and exposed to

the organs of absorption in that region. If the enemata are large,

the digestive and absorptive processes are by no means confined to

the colon, but may take place along extensive surfaces of the small

intestine. I have repeatedly seen rhythmic segmentation active

throughout many loops of the small intestine, thus exposing the

injected food to the same mixing and absorbing processes as affect the

nutriment which has come through the stomach in a normal manner.

THE EFFECT OF EMOTIONS AND SLEEP

Observations on the stomach of the cat showed that the peristalsis

is inhibited whenever the animal manifests signs of anxiety, rage,

or distress. Since the extrinsic innervation of a large part of

the intestinal tract is the same as that of the stomach, it is of

interest to note the effect of emotional states on the movements of

the intestines. Esselmont, in a study of the dog’s intestine, noted

constantly after signs of emotion a marked increase of activity lasting

for only a few moments. Fubini also observed that fear occasioned more

rapid peristalsis. There is no doubt that many emotional states are

a strong stimulus to peristalsis, but it is equally true that other

emotional states inhibit peristalsis. In the cat the same conditions

which stop the movements of the stomach stop also the movements of the

intestines.

[Illustration:

FIGURE 10.--Tracings showing the effect of excitement on

antiperistalsis in the colon.]

The female cats used in these observations ordinarily lie quietly on

the holder and make no demonstration. Sometimes, however, with only a

little premonitory restlessness, the cat suddenly flies into a rage,

lashing her tail from side to side, pulling and jerking with every

limb, and biting at everything near her head. During such excitement,

and for some moments after the animal becomes pacified again, the

movements, both of the large and small intestine, entirely cease. Such

violence of excitement is not necessary to cause the movements to stop;

a cat which was restless and continually whining while confined to the

holder showed no signs of intestinal movements during any period of

observation (one period lasted more than an hour), although the changes

in the distribution of the food observable from one period to the next

proved that movements were going on during the quiet intermissions.

In another cat, uneasy and fretful for fifty minutes, no activity was

seen; then she became quiet for several minutes, and peristalsis of the

small intestine appeared.

When the segmentation process in the small intestine is stopped by

excitement the segments unite and the series of parts returns to the

form of a solid string. The change occurring in the large intestine

when the antiperistalsis is inhibited by excitement is shown in Figure

10. The tonic constrictions in the descending colon are apparently not

affected by emotional states, for they do not seem to relax in the

excitement which causes the movements to cease.

By holding the mouth and nostrils closed, or by pressing between the

rami of the jaw, the breathing may be stopped. As soon as the cat shows

distress from lack of breath every form of intestinal movement stops.

The statement is sometimes made in text-books of physiology that the

gastric and intestinal mechanisms cease to act during sleep. It is

worthy of note that nearly all the animals curled up and slept during

the time between observations; nevertheless, the progress of the food

through the intestines continued. The statement is also made that at

night, even without sleep, the intestines are almost entirely at rest;

that this is their normal time for repose. I have seen both large and

small intestines actively at work, however, from half past nine until

half past ten o’clock at night.

SUMMARY

1. Bismuth subnitrate, 10 to 33 per cent, mixed with the food renders

the movement of the intestinal contents, and thereby the movements of

the intestinal walls, visible on the fluorescent screen.

2. The activity most commonly seen in the small intestine is the

simultaneous division of the food in a coil into small segments, and

a rhythmic repetition of the segmentation each time applied to the

new segments formed from parts of those just divided. In the cat this

rhythmic segmentation may proceed at the rate of thirty divisions per

minute. The effects of the constrictions causing the segmentation are

the mixing of the food and the digestive juices, the bringing of the

digested food into contact with the absorbing mechanisms, and the

emptying of the venous and lymphatic radicles of their contents by

compression of the intestinal wall.

3. Peristalsis is usually combined with segmentation. As the food is

advancing, interfering constrictions often separate the rear end of the

mass from the main body. The separation is momentary, however; the

rear end is swept into union with the main body again, and the whole

mass is pushed onward until another constriction repeats the changes.

4. The ileocæcal valve is thoroughly competent for food entering the

colon from the ileum.

5. The usual movement of the transverse and ascending colon and the

cæcum is an antiperistalsis. This recurs in periods about every fifteen

minutes, and each period lasts commonly about five minutes; the waves

recur during a period at the rate usually of eleven waves in two

minutes. This antiperistalsis gives new significance to the ileocæcal

valve; for the food, now in a closed sac, is thoroughly churned and

mixed by the constrictions running towards the cæcum, and again exposed

to absorbing walls without any interference with the processes in the

small intestine.

6. As soon as new food enters the large intestine a strong general

contraction takes place along the cæcum and ascending colon, forcing

some of the food onward; a moment later antiperistaltic waves begin to

pass.

7. With the accumulation of material in the transverse colon, deep

tonic constrictions appear one after another and carry the material

into the descending colon, leaving the transverse and ascending

portions free for the antiperistaltic waves.

8. In emptying the large intestine the material in the lower descending

colon is first carried out by combined peristalsis and pressure of

abdominal muscles; the remainder of the material is then spread into

the evacuated region, and this region is again cleared; the second

remainder may be similarly affected. In normal life the new food

arriving in the colon must force forward the old contents of the

ascending and transverse colon.

9. The observations have revealed no evidence of antiperistalsis in

the small intestine, but since the ileocæcal valve will allow nutrient

material under pressure to pass backward, the antiperistalsis of the

large intestine may force into the small intestine a considerable

portion of a large nutrient enema. Segmentation in the small intestine

affects such an enema precisely as it affects food which has passed

normally through the stomach.

10. Signs of emotion, such as fear, distress, or rage, are accompanied

by a total cessation of the movements of both large and small

intestines. The movements continue in the cat both during sleep and at

night.

THE BATTLE CREEK LABORATORIES

THE MAMMOTH SANITARIUM AND THE LARGE ADOPTED FAMILY OF DR. AND MRS. J.

H. KELLOGG

[A report of one experiment has been selected from _Modern Medicine_

relative to the work of the laboratories connected with the Battle

Creek Sanitarium because it relates to the effect of cooking and

mastication upon food in illustration of the statement of Dr. Campbell

pertaining to these aids to digestion. Much more evidence could be had

from the Sanitarium reports, but sufficient has already been given

herewith from various authoritative sources to justify our claims of

the great importance of mouth-treatment in human nutrition.

It may be said here, however, that the trial of thorough mouth-work as

an aid to digestion, which has been in progress at the Sanitarium for

more than a year, and which has finally been accepted and prescribed

as the first requirement of the treatment of patients, is of the

utmost significance. This is, by far, the largest sanitarium in the

world, having some hundreds of physicians, nurses, and other attachés,

and treating many thousands of patients annually. The “cure” is based

upon natural methods of recuperation, and while all of the staff, both

medical and surgical, are fully equipped diplomatists, and whereas the

organisation has a legally and professionally accepted medical school

of its own, so-called medicines are rarely used, and never except as

antidotes to specific poisons. Nature is assisted by scientific means

to do the curing, and now that an economic nutrition to relieve the

exhausted system of the patient from all possible strain through ample

mouth-treatment of food, as intended by the anatomical, dental, and

chemical plan on which man is constructed, has been tried and accepted

as a fundamental principle of the institution, it gives a practical

indorsement of the claims set forth in “Glutton or Epicure,” and in

this present book, and declares that they are of greatest importance

in securing health and efficiency.

The Battle Creek Sanitarium is a philanthropic and humanitarian

institution operating under a perpetual charter which compels the use

of all the profits gained to foster the spread of the humanitarian

work. More than sixty branches of the parent institution have been

established in or near large cities in different parts of the world,

under the title of The American Medical Missionary Association,

and each of these branches conducts a life-saving business on Good

Samaritan principles. The organisation started its medical missionary

work some thirty-seven years ago, with almost no capital and only

one patient, in a small two-storey frame house, in the then small

village of Battle Creek, Michigan. The incorporators were religious

enthusiasts who believed that Christianity should be expressed in

works as much as in faith, in curing the sick and healing the wounded,

and thus preparing the unfortunate for the reception of moral and

spiritual inspiration.

The best evidence that this scheme of procedure to attain the ultimate

end was a good one is shown by the success of the institution in

its growth from such small beginning to the immense proportions of

the present time, with one of its buildings nearly a thousand feet

in length and five storeys in height and numerous other buildings

radiating from the main one and scattered about it in a finely wooded

park. Fire came and destroyed the old building and all its contents,

but yet it was soon rebuilt, and the concern goes on growing and

growing, because the foundation principle of the institution is the

beautiful Golden Rule, and the method of treatment employed is taken

from the open book of Nature.

While the organisation was primarily based upon a special religious

creedal enthusiasm, it has become so broadly altruistic as to suggest

a return to original Christianity as defined in the Sermon on the

Mount. In such Christian expression honest agnostics, born Buddhists,

and the tolerant of all the different Christian creeds may join and

say amen!

One of the splendid results of an economic nutrition, attained by

following the natural requirements and impulses, is the curing of

many diseases, among them several forms of constipation. The writer

has a genuine admiration for the spirit that is the motive power

of the Battle Creek Sanitarium and firm belief in the Christianity

demonstrated in the work, especially in the private experiment of Dr.

and Mrs. Kellogg, with their family of adopted waifs. Twenty-four

children of unfortunate parents, waifs so unfortunate in their

attractability as to be hopelessly neglected, have been gathered

under this sheltering roof and are showing their mettle and gratitude

by splendid behaviour and brilliant accomplishment in a manner that

any proud parent might approve. To miss any opportunity to express

gratitude to Dr. and Mrs. Kellogg for giving us such a splendid

example of the true meaning of practical Christianity would be showing

symptoms of the worst form of constipation; viz., constipation of

appreciation and affection.—HORACE FLETCHER.]