the chemical activity of the body is increased 10 per cent. In acute infections there is aversion to food and frequently there is vomiting. In fever, then, we have diminished intake of energy, but an increased output of energy–hence the available potential energy in the body is rapidly consumed. This may be an adaptation for the purpose of breaking up the foreign protein molecules composing the bacteria. Thus the body may be purified by a chemical combustion so furious that frequently the host itself is destroyed. The problems of immunity are not considered here.
As to the mechanism which produces fever, we postulate that it is the same mechanism as that which produces muscular activity. Muscular activity is produced by the conversion of latent energy into motion, and fever is produced largely in the muscles by the conversion of latent energy into heat. We should, therefore, find similar changes in the brain, the adrenals, the thyroid, and the liver, whatever may be the purpose of the conversion of energy– whether for running, for fighting, for the expression of emotion, or for combating infection.
We shall first present experimental and clinical evidence which tends to show what part is played by the brain in the production of both muscular and febrile action, and later we shall discuss the parts played by the adrenals, the thyroid, and the liver. Histologic Changes in the Brain-cells in Relation to the Maintenance of Consciousness and to the Production of the Emotions, Muscular Activity, and Fever
We have studied the brain-cells in human cases of fever, and in animals after prolonged insomnia; after the injection of the toxins of gonococci, of streptococci, of staphylococci, and of colon, tetanus, diphtheria, and typhoid bacilli; and after the injection of foreign proteins, of indol and skatol, of leucin, and of peptones. We have studied the brains of animals which had been activated in varying degrees up to the point of complete exhaustion by running, by fighting, by rage and fear, by physical injury, and by the injection of strychnin (Figs. 2, 4, 5, and 37). We have studied the brains of salmon at the mouth of the Columbia River and at its headwater (Fig. 55); the brains of electric fish, the storage batteries of which had been partially discharged, and of those the batteries of which had been completely discharged; the brains of woodchucks in hibernation and after fighting; the brains of humans who had died from anemia resulting from hemorrhage, from acidosis, from eclampsia, from cancer and from other chronic diseases (Figs. 40 to 43, 56, 74, and 75). We have studied also the brains of animals after the excision of the adrenals, of the pancreas, and of the liver (Figs. 57 and 60).
In every instance the loss of vitality–that is, the loss of the normal power to convert potential into kinetic energy– was accompanied by physical changes in the brain-cells (Figs. 45 and 46). The converse was also true, that is, the brain-cells of animals with normal vital power showed no histologic changes. The changes in the brain-cells were identical whatever the cause. The crucial question then becomes: Are these constant changes in the brain-cells the result of work done by the brain-cells in running, in fighting, in emotion, in fever? In other words, does the brain perform a definite role in the conversion of latent energy into fever or into muscular action; or are the brain-cell changes caused by the chemical products of metabolism? Happily, this crucial question was definitely answered by the following experiment: The circulations of two dogs were crossed in such a manner that the circulation of the head of one dog was anastomosed with the circulation of the body of another dog, and vice versa. A cord encircled the neck of each so firmly that the anastomosing circulation was blocked (Fig. 58). If the brain-cell changes were due to metabolic products, then when the body of dog “A” was injured, the brain of dog “A” would be normal and the brain of dog “B” would show changes. Our experiments showed brain-cell changes in the brain of the dog injured and no changes in the brain of the uninjured dog.
The injection of adrenalin causes striking brain-cell changes: first, a hyperchromatism, then a chromatolysis. Now if adrenalin caused these changes merely as a metabolic phenomenon and not as a “work” phenomenon, then the injection of adrenalin into the carotid artery of a crossed circulation dog would cause no change in its circulation and its respiration, since the brain thus injected is in exclusive vascular connection with the body of another dog. In our experiment the blood-pressures of both dogs were recorded on a drum when adrenalin was injected into the common carotid. The adrenalin caused a rise in blood-pressure, an increase in the force of cardiac contraction, increase in respiration, and a characteristic adrenalin rise in the blood-pressure of both dogs. The rise was seen first in the dog whose brain alone received adrenalin and about a minute later in the dog whose body alone received adrenalin (Fig. 59). Histologic examinations of the brains of both dogs showed marked hyperchromatism in the brain receiving adrenalin, while the brain receiving no adrenalin showed no change. Here is a clear-cut observation on the action of adrenalin on the brain, for both the functional and the histologic tests showed that adrenalin causes increased brain action. The significance of this affinity of the brain for adrenalin begins to be seen when I call attention to the following striking facts:
1. Adrenalin alone causes hyperchromatism followed by chromatolysis, and in overdosage causes the destruction of some brain-cells.
2. When both adrenal glands are excised and no other factor is introduced, the Nissl substance progressively disappears from the brain-cells until death. This far-reaching point will be taken up later (Fig. 60).
Here our purpose is to discuss the cause of the brain-cell changes. We have seen that in crossed brain and body circulation trauma causes changes in the cells of the brain which is disconnected from the traumatized body by its circulation, but which is connected with the traumatized body by the nervous system. We have seen that adrenalin causes activation of the body connected with its brain by the nervous system, and histologic changes in the brain acted on directly by the adrenalin, but we found no notable brain-cell changes in the other brain through which the products of metabolism have circulated.
In the foregoing we find direct evidence that the products of metabolism are not the principal cause of the brain-cell changes. We shall now present evidence to show that for the most part the brain-cell changes are “work” changes. What work? We postulate that it is the work by which the energy stored in the brain-cells is converted into electricity or some other form of transmissible energy which then activates certain glands and muscles, thus converting latent energy into beat and motion. It has chanced that certain other studies have given an analogous and convincing proof of this postulate. In the electric fish a part of the muscular mechanism is replaced by a specialized structure for storing and discharging electricity. We found “work” changes in the brain-cells of electric fish after all their electricity had been rapidly discharged (Fig. 61). We found further that electric fish could not discharge their electricity when under anesthesia, and clinically we know that under deep morphin narcosis, and under anesthesia, the production both of heat and of muscular action is hindered. The action of morphin in lessening fever production is probably the result of its depressing influence on the brain-cells, because of which a diminished amount of their potential energy is converted into electricity and a diminished electric discharge from the brain to the muscles should diminish heat production proportionally. We found by experiment that under deep morphinization brain-cell changes due to toxins could be largely prevented (Fig. 62); in human patients deep morphinization diminishes the production of muscular action and of fever and conserves life when it is threatened by acute infections. The contribution of the brain-cells to the production of heat is either the result of the direct conversion of their stored energy into heat, or of the conversion of their latent energy into electricity or a similar force, which in turn causes certain glands and muscles to convert latent energy into heat.
A further support to the postulate that the brain-cells contribute to the production of fever by sending impulses to the muscles is found in the effect of muscular exertion, or of other forms of motor stimulation, in the presence of a fever-producing infection. Under such circumstances muscular exertion causes additional fever, and causes also added but identical changes in the brain-cells. Thyroid extract and iodin have the same effect as muscular exertion and infection in the production of fever and the production of brain-cell changes. All this evidence is a strong argument in favor of the theory that certain constituents of the brain-cells are consumed in the work performed by the brain in the production of fever.
That the stimulation of the brain-cells without gross activity of the skeletal muscles and without infection can produce heat is shown as follows:
(_a_) Fever is produced when animals are subjected to fear without any consequent exertion of the skeletal muscles.
(_b_) The temperature of the anxious friends of patients will rise while they await the outcome of an operation (Fig. 63).
(_c_) The temperature and pulse of patients will rise as a result of the mere anticipation of a surgical operation (Fig. 64).
(_d_) There are innumerable clinical observations as to the effect of emotional excitation on the temperature of patients. A rise of a degree or more is a common result of a visit from a tactless friend. There is a traditional Sunday increase of temperature in hospital wards. Now the visitor does not bring and administer more infection to the patient to cause this rise, and the rise of temperature occurs even if the patient does not make the least muscular exertion as a result of the visit. I once observed an average increase of one and one-eighth degrees of temperature in a ward of fifteen children as a result of a Fourth of July celebration.
Is the contribution of the brain to the production of heat due to the conversion of latent energy directly into heat, or does the brain produce heat principally by converting its latent energy into electricity or some similar form of transmissible energy which, through nerve connections, stimulates other organs and tissues, which in turn convert their stores of latent energy into heat?
According to Starling, when the connection between the brain and the muscles of an animal is severed by curare, by anesthetics, by the division of the cord and nerves, then the heat-producing power of the animal so modified is on a level with that of cold-blooded animals. With cold the temperature falls, with heat it rises. Such an animal has no more control over the conversion of latent energy into heat than it has over the conversion of latent energy into motion.
Electric stimulation done over a period of time causes brain-cell changes, and electric stimulation of the muscles causes a rise in temperature.
Summary of Brain-cell Studies
In our crossed circulation experiments we found that neither waste products nor metabolic poisons could be considered the principal cause of the brain-cell changes. We found that in the production both of muscular action and of fever there were brain-cell changes which showed a quantita-tive relation to the temperature changes or to the muscular work done. We observed that under deep morphinization the febrile response or the muscular work done was either diminished or eliminated and that the brain-cell changes were correspondingly diminished or eliminated. We found also that brain-cell changes and muscular work followed electric stimulation alone. I conclude, therefore, that the brain-cell changes are work changes.
We shall next consider other organs of the kinetic system in their relation to muscular activity, to emotion, to consciousness, to sleep, to hibernation, and to heat production.
The Adrenals
In our extensive study of the brain in its relation to the production of energy and the consequent exhaustion caused by fear and rage; by the injection of foreign proteins, of bacterial toxins, and of strychnin; by anaphylaxis; by the injection of thyroid extract, of adrenalin, and of morphin, we found that, with the exception of morphin, each of these agents produced identical changes in the brain-cells. As we believed that the adrenals were intimately associated with the brain in its activities, we concluded that the adrenals also must have been affected by each of these agents. To prove this relation, we administered the above-mentioned stimuli to animals and studied their effects upon the adrenals by functional, histologic, and surgical methods, the functional tests being made by Cannon’s method.
Functional Study of the Adrenals.–Our method of applying the Cannon test for adrenalin was as follows: (_a_) The blood of the animals was tested before the application of the stimulus. If this test was negative, then (_b_) the stimulus was applied and the blood again tested. If this second test was negative, a small amount of adrenalin was added. If a positive reaction was then given, the negative result was accepted as conclusive. (_c_) If the control test was negative, then the stimulus was given. If the blood after stimulation gave a positive result for adrenalin, a second test of the same animal’s blood was made twenty-five minutes or more later. If the second test was negative, then the positive result of the first test was accepted as conclusive.
We have recorded 66 clear-cut experiments on dogs, which show that after fear and rage, after anaphylaxis, after injections of indol and skatol, of leucin and creatin, of the toxins of diphtheria and colon bacilli, of streptococci and staphylococci, of foreign proteins, and of strychnin, the Cannon test for adrenalin was positive. The test was negative after trauma under anesthesia, and after intravenous injections of thyroid extract, of thyroglobin, and of the juices of various organs injected into the same animal from which the organs were taken. Placental extract gave a positive test. The test was sometimes positive after electric stimulation of the splanchnic nerves. On the other hand, if the nerve supply to the adrenals had been previously divided, or if the adrenals had been previously excised, then the Cannon test was negative after the administration of each of the foregoing adequate stimuli. Blood taken directly from the adrenal vein gave a positive result, but under deep morphinization the blood from the adrenal vein was negative, and under deep morphinization the foregoing adequate stimuli were negative.
In brief, the agencies that in our brain-cell studies were found to cause hyperchromatism followed by chromatolysis gave positive results in the Cannon test for adrenalin (Fig. 62). The one agent which was found to protect the brain against changes in the Nissl substance– morphin–gave a negative result in the Cannon test for adrenalin. After excision of the adrenals, or after division of their nerve supply, all Cannon tests for adrenalin were negative.
Histologic Study of the Adrenals.–Histologic studies of the adrenals after the application of the adequate stimuli which gave positive results to the Cannon test for adrenalin are now in progress, and thus far the histologic studies corroborate the functional tests.
In hibernating woodchucks, the cells of the adrenal cortex were found to be vacuolated and shrunken. In one hundred hours of insomnia, in surgical shock, in strong fear, in exhaustion from fighting, after peptone injections, in acute infections, the adrenals undergo histologic changes characteristic of exhaustion (Figs. 66 to 67).
We have shown that brain and adrenal activity go hand in hand, that is, that the adrenal secretion activates the brain, and that the brain activates the adrenals. The fundamental question which now arises is this: Are the brain and the adrenals interdependent? A positive answer may be given to this question, for the evidence of the dependence of the brain upon the adrenals is as clear as is the evidence of the dependence of the adrenals upon the brain. (1) After excision of the adrenals, the brain-cells undergo continuous histologic and functional deterioration until death. During this time the brain progressively loses its power to respond to stimuli and there is also a progressive loss of muscular power and a diminution of body temperature. (2) {illust. caption = FIG. 66.In our crossed circulation experiments we found that adrenalin alone could cause increased brain activity, while histologically we know that adrenalin alone causes an increase of the Nissl substance. An animal, both of whose adrenals had been excised, showed no hyperchromatism in the brain-cells after the injection of strychnin, toxins, foreign proteins, etc. (3) When the adrenal nerve supply is divided (Cannon-Elliott), then there is no increased adrenal activity in response to adequate stimuli.
From these studies we are forced to conclude not only that the brain and adrenals are interdependent, but that the brain is actually more dependent upon the adrenals than the adrenals upon the brain, since the brain deteriorates progressively to death without the adrenals, while the adrenal whose connection with the brain has been broken by the division of its nerve supply will still produce sufficient adrenalin to support life.
From the strong affinity of the brain-cells for adrenalin which was manifested in our experiments we may strongly suspect that the Nissl substance is a volatile, extremely unstable combination of certain elements of the brain-cells and adrenalin, because the adrenals alone do not take the Nissl stain and the brain deprived of adrenalin also does not take Nissl stain. The consumption of the Nissl substance in the brain-cells is lessened or prevented by morphin, as is the output of adrenalin; and the consumption of the Nissl substance is also lessened or prevented by nitrous oxid. But morphin does not prevent the action of adrenalin injected into the circulation, hence the control of morphin over energy expenditure is exerted directly on the brain-cells. Apparently morphin and nitrous oxid both act through this interference with oxidation in the brain. We, therefore, conclude that within a certain range of acidity of the blood adrenalin can unite with the brain-cells only through the mediation of oxygen, and that the combination of adrenalin, oxygen, and certain brain-cell constituents causes the electric discharge that produces heat and motion. In this interrelation of the brain and the adrenals we have what is, perhaps, the master key to the automatic action of the body. Through the special senses environmental stimuli reach the brain and cause it to liberate energy, which in turn activates certain other organs and tissues, among which are the adrenals. The increased output of adrenalin activates the brain to still greater activity, as a result of which again the entire sympathetic nervous system is further activated, as is manifested by increased heart action, more rapid respiration, raised blood-pressure, increased output of glycogen, increased power of the muscles to metabolize glucose, etc.
If this conclusion be well founded, we should find corroborative evidence in histologic changes in that great storehouse of potential energy, the liver, as a result of the application of each of the adequate stimuli which produced brain-cell and adrenal changes.
The Liver
Prolonged insomnia, prolonged physical exertion, infections, injections of toxins and of strychnin, rage and fear, physical injury under anesthesia, in fact, all the adequate stimuli which affected the brain and the adrenals, produced constant and identical histologic changes in the liver–the cells stained poorly, the cytoplasm was vacuolated, the nuclei were crenated, the cell membranes were irregular, the most marked changes occurring in the cells of the periphery of the lobules (Figs. 69 and 70). In prolonged insomnia the striking changes in the liver were repaired by one seance of sleep.
Are the histologic changes in the liver cells due to metabolism or toxic products, or are they “work” changes incident to the conversion of latent into kinetic energy? Are the brain, adrenals, and liver interdependent? The following facts establish the answers to these queries:
(1) The duration of life after excision of the liver is about the same as after adrenalectomy–approximately eighteen hours.
(2) The amount of glycogen in the liver was diminished in all the experiments showing brain-adrenal activity; and when the histologic changes were repaired, the normal amount of glycogen was again found.
(3) In crossed circulation experiments changes were found in the liver of the animal whose brain received the stimulus.
From these premises we must consider that the brain, the adrenals, and the liver are mutually dependent on one another for the conversion of latent into kinetic energy. Each is a vital organ, each equally vital. It may be said that excision of the brain may apparently cause death in less time than excision of the liver or adrenals, but this statement must be modified by our definition of death. If all the brain of an animal be removed by decapitation, its body may live on for at least eleven hours if its circulation be maintained by transfusion. An animal may live for weeks or months after excision of the cerebral hemispheres and the cerebellum, while an overtransfused animal may live many hours, days even, after the destruction of the medulla. It is possible even that the brain actually is a less vital organ than either the adrenals or the liver.
In our research to discover whether any other organs should be included with the brain, the adrenals, and the liver in this mutually interdependent relation, we hit upon an experiment which throws light upon this problem.
Groups of rabbits were gently kept awake for one hundred hours by relays of students, an experiment which steadily withdrew energy but caused not the slightest physical or emotional injury to any of them; no drug, toxin, or other agent was given to them; they were given sufficient food and drink. In brief, the internal and external environments of these animals were kept otherwise normal excepting for the gentle stimuli which insured continued wakefulness. This protracted insomnia gradually exhausted the animals completely, some to the point of death even. Some of the survivors were killed immediately after the expiration of one hundred hours of wakefulness, others after varying intervals.
Histologic studies were made of every tissue and organ in the body. Three organs, the brain, the adrenals, and the liver, and these three only, showed histologic changes. In these three organs the histologic changes were marked, and were almost wholly repaired by one seance of sleep. In each instance these histologic changes were identical with those seen after physical exertion, emotions, toxins, etc.[*] It would appear, then, that these three organs take the stress of life– the brain is the “battery,” the adrenals the “oxydizer,” and the liver the “gasoline tank.” This clear-cut insomnia experiment corresponds precisely with our other brain-adrenal observations.
[*] Further studies have given evidence that the elimination of the acids resulting from energy-transformation as well as the conversion of energy stored in the kinetic organs causes histologic changes in the liver, the adrenals, and possibly in the brain.
With these three kinetic organs we may surely associate also the “furnace,” the muscles, in which the energy provided by the brain, adrenals, and liver, plus oxygen, is fabricated into heat and motion.
Benedict, in his monumental work on metabolism, has demonstrated that in the normal state, at least, variations in the heart-beat parallel variations in metabolism. He and others have shown also that all the energy of the body, whether evidenced by heat or by motion, is produced in the muscles. In the muscles, then, we find the fourth vital link in the kinetic chain. The muscles move the body, circulate the blood, effect respiration, and govern the body temperature. They are the passive servants of the brain-adrenal-liver syndrome.
Neither the brain, the adrenals, the liver, nor the muscles, however, nor all of these together, have the power to change the rate of the expenditure of energy; to make possible the increased expenditure in adolescence, in pregnancy, in courting, and mating, in infections. No one of these organs, nor all of them together, can act as a pace-maker or sensitizer. The brain acts immediately in response to the stimuli of the moment; the adrenals respond instantly to the fickle brain and the effects of their actions are fleeting; the liver contains fuel only and cannot activate, and the muscles in turn act as the great furnace in which the final transformation into available energy is made. The Thyroid
Another organ–the thyroid–has the special power of governing the RATE OF DISCHARGE of energy; in other words, the thyroid is the pace-maker. Unfortunately, the thyroid cannot be studied to advantage either functionally or histologically, for there is as yet no available test for thyroid secretion in the blood as there is for adrenalin, and thyroid activity is not attended by striking histologic changes. Therefore the only laboratory studies which have been satisfactory thus far are those by which the iodin content of the thyroid has been established. Iodin is stored in the colloid lacunae of the thyroid and, in combination with certain proteins, is the active agent of the thyroid.
Beebe has shown that electric stimulation of the nerve supply of the thyroid diminishes the amount of iodin which it contains, and it is known that in the hyperactive thyroid in Graves’ disease the iodin content is diminished. The meagerness of laboratory studies, however, is amply compensated by the observations which the surgeon has been able to make on a vast scale–observations which are as definite as are the results of laboratory experiments.
The brain-cells and the adrenals are securely, concealed from the eye of the clinician, hence the changes produced in them by different causes escape his notice, but the thyroid has always been closely scrutinized by him. The clinician knows that every one of the above-mentioned causes of increased brain-cell, adrenal, liver and muscle activity may cause an increase in the activity of both the normal or the enlarged thyroid; and lie knows only too well that in a given case of exophthalmic goiter the same stimuli which excite the brain, the adrenals, the liver, and the muscles to increased activity will also aggravate this disease.
The function of the thyroid in the kinetic chain is best evidenced, however, by its role in the production of fever. Fever results from the administration of thyroid extract alone in large doses. In the hyperactivity of the thyroid in exophthalmic goiter one sees a marked tendency to fever, in severe cases there is daily fever. In fact, in Graves’ disease we find displayed to an extraordinary degree an exaggeration of the whole action of the kinetic mechanism.
We have stated that in acute Graves’ disease there is a tendency to the production of spontaneous fever, and that there is a magnified diurnal variation in temperature which is due to an increased output of energy in even the normal reaction producing consciousness. In Graves’ disease there is, therefore, a state of intensified consciousness, which is associated with low brain thresholds to all stimuli–both to stimuli that cause muscular action and to stimuli that cause fever. The intensity of the kinetic discharge is seen in the constant fine tremor. It is evident that the thresholds of the brain have been sensitized. In this hypersensitization we find the following strong evidence as to the identity of the various mechanisms for the production of fever. In the state of superlative sensitization which is seen in Graves’ disease we find that the stimuli that produce muscular movement, the stimuli that produce emotional phenomena, and the stimuli that produce fever are as nearly as can be ascertained equally effective. Clinical evidence regarding this point is abundant, for in patients with Graves’ disease we find that the three types of conversion of energy resulting from emotional stimulation, from infection stimulation, and from nociceptor stimulation (pain), are, as nearly as can be judged, equally exaggerated. In the acute cases of Graves’ disease the explosive conversion of latent energy into heat and motion is unexcelled by any other known normal or pathologic phenomenon. Excessive thyroid secretion, as in thyrotoxicosis from functioning adenomata, and excessive thyroid feeding, cause all the phenomena of Graves’ disease except the exophthalmos and the emotional facies (Figs. 15 and 23). The ligation of arteries, the division of its nerve supply, or the excision of part of the gland, may reverse the foregoing picture and restore the normal condition. The patient notes the effect on the second day and often within a week is relatively quiescent. On the contrary, if there is thyroid deficiency there results the opposite state, a reptilian sluggishness.
At will, then, through diminished, normal, or excessive administration of thyroid secretion, we may produce an adynamic, a normal, or an excessively dynamic state. By the thyroid influence, the brain thresholds are lowered and life becomes exquisite; without its influence the brain becomes a globe of relatively inert substance. Excessive doses of iodin alone cause most of the symptoms of Graves’ disease. As we have stated, the active constituent of the thyroid is iodin in a special protein combination which is stored in the colloidal spaces. Hence one would not expect to find changes in the cells of the thyroid gland as a result of increased activity unless it be prolonged.
We have thus far considered the normal roles played by the brain, the adrenals the liver, the muscles, and the thyroid in transforming latent into kinetic energy in the form of heat and motion as an adaptive response to environmental stimuli.
The argument may be strengthened, however, by the discussion of the effect of the impairment of any of these links in the kinetic chain upon the conversion of latent into kinetic energy.
Effect Upon the Output of Energy of Impaired or Lost Function of Each of the Several Links in the Kinetic Chain
(1) _The Brain_.–In cerebral softening we may find all the organs of the body comparatively healthy excepting the brain. As the brain is physically impaired it cannot normally stimulate other organs to the conversion of latent energy into heat or into motion, but, on the contrary, in these cases we find feeble muscular and intellectual power. I believe also that in patients with cerebral softening, infections such as pneumonia show a lower temperature range than in patients whose brains are normal.
(2) _The Adrenals_.–In such destructive lesions of the adrenals as Addison’s disease one of the cardinal symptoms is a subnormal temperature and impaired muscular power. Animals upon whom double adrenalectomy has been performed show a striking fall in temperature, muscular weakness,–after adrenalectomy the animal may not be able to stand even,–and progressive chromatolysis.
(3) _The Liver_.–When the function of the liver is impaired by tumors, cirrhosis, or degeneration of the liver itself, then the entire energy of the body is correspondingly diminished. This diminution of energy is evidenced by muscular and mental weakness, by diminished response and by gradual loss of efficiency which finally reaches the state of asthenia.
(4) _The Muscles_.–It has been observed clinically that if the muscles are impaired by long disuse, or by a disease such as myasthenia gravis, then the range of production of both heat and motion is below normal. This is in agreement with the experimental findings that anesthetics, curare, or any break in the muscle-brain connection causes diminished muscular and heat production.
(5) _The Thyroid_.–In myxedema one of the cardinal symptoms is a persistently subnormal temperature and, though prone to infection, subjects of myxedema show but feeble febrile response and readily succumb. This clinical observation is strikingly confirmed by laboratory observations; normal rabbits subjected to fear showed a rise in temperature of from one to three degrees, while two rabbits whose thyroids had been previously removed and who had then been subjected to fright showed much less febrile response. Myxedema subjects show a loss of physical and mental energy which is proportional to the lack of thyroid. Deficiency in any of the organs of the kinetic chain causes alike loss of heat, loss of muscular and emotional action, of mental power, and of the power of combating infections–the negative evidence thus strongly supports the positive. By accumulating all the evidence we believe we are justified in associating the brain, the adrenals, the thyroid, the muscles, and the liver as vital links in the kinetic chain. Other organs play a role undoubtedly, though a minor one.
Studies in Hydrogen Ion Concentration in Activation of the Kinetic System
Having established the identity of some, at least, of the organs which constitute the kinetic chain, we endeavored to secure still further evidence regarding the energy-transforming function of these organs by making studies of the H-ion concentration of the blood, as one would expect, _prima facie_, that the normal reaction would be altered by kinetic activation.[*]
[*] The H-ion observations were made in my laboratory by Dr. M. L. Menten.
H-ion concentration tests were made after the application of the adequate stimuli by which the function of the kinetic organs had been determined, and we studied also the effect upon the acidity of the blood of strychnin convulsions after destruction of the medulla; of deep narcotization with morphin before anesthesia; of deep narcotization with morphin after the H-ion concentration had already been increased by fear, by anger, by exertion, by injury under anesthesia, or by anesthesia alone.
The complete data of these experiments will be later reported in a monograph; here it is sufficient to state that anger, fear, injury, muscular exertion, inhalation anesthesia, strychnin, alcohol, in fact, all the stimuli which we had already found to produce histologic changes in the brain, the adrenals, and the liver-excepting bacterial toxins–caused increased H-ion concentration. Of striking significance is the fact that morphin alone caused no change in the H-ion concentration, while if administered before the application of a stimulus which by itself produced increased H-ion concentration, the action of that stimulus was neutralized or postponed. If, however, morphin was administered after increased acidity had been produced by any stimulus, or by inhalation anesthesia, then the time required for the restoration of the normal alkalinity was much prolonged, and in some instances the power of acid neutralization was permanently lost.
After excision of the liver, the normal H-ion concentration was maintained for periods varying from one to several hours, after which the concentration (acidity) began to increase as the vitality of the animal began to decline, the concentration (acidity) increasing rapidly until death. After excision of the adrenals the blood remained normal for from four to six hours, when the H-ion concentration increased rather suddenly, the increase being synchronous with the incidence of the phenomena which immediately preceded death.
In none of these cases was it determined whether the increased H-ion concentration was due to other causes of death or whether death was due to the increased acidity.
It is also significant that after the application of each of the adequate stimuli which increased the H-ion concentration of the blood in other parts of the body the blood from the adrenal vein showed a slight diminution in acidity, as, in most instances, did the blood from the hepatic vein also.
In fact, the H-ion concentration of the blood in the adrenal vein was less than in the blood of any other part of the circulation.
Kinetic Diseases
If our conclusions are sound, then in the kinetic system we find an explanation of many diseases, and having found the explanation, we may find new methods of combating them.
When the kinetic system is driven at an overwhelming rate of speed,– as by severe physical injury, by intense emotional excitation, by perforation of the intestines, by the pointing of an abscess into new territory, by the sudden onset of an infectious disease, by an overdose of strychnin, by a Marathon race, by a grilling fight, by foreign proteins, by anaphylaxis,–the result of these acute overwhelming activations of the kinetic system is clinically designated shock, and according to the cause is called traumatic shock, toxic shock, anaphylactic shock, drug shock, etc.
The essential pathology of shock is identical whatever the cause. If, however, instead of an intense overwhelming activation, the kinetic system is continuously or intermittently overstimulated through a considerable period of time, as long as each of the links in the kinetic chain takes the strain equally the result will be excessive energy conversion, excessive work done; but usually, under stress, some one link in the chain is unable to take the strain and then the evenly balanced work of the several organs of the kinetic system is disturbed. If the brain cannot endure the strain, then neurasthenia, nerve exhaustion, or even insanity follows. If the thyroid cannot endure the strain, it undergoes hyperplasia, which in turn may result in a colloid goiter or in exophthalmic goiter. If the adrenals cannot endure the strain, cardiovascular disease may develop. If the liver cannot take the strain, then death from acute acidosis may follow, or if the neutralizing effect of the liver is only partially lost, then the acidity may cause Bright’s disease. Overactivation of the kinetic system may cause glycosuria and diabetes.
Identical physical and functional changes in the organs of the kinetic system may result from intense continued stimulation from any of the following causes: Excessive physical labor, athletic exercise, worry or anxiety, intestinal autointoxication, chronic infections, such as oral sepsis, tonsillitis, and adenoids; chronic appendicitis, chronic cholecystitis, colitis, and skin infections; the excessive intake of protein food (foreign protein reaction); emotional strain, pregnancy, stress of business or professional life– all of which are known to be activators of the kinetic system.
From the foregoing statements we are able to understand the muscular weakness following fever; we can understand why the senile have neither muscular power nor strong febrile reaction; why long-continued infections produce pathologic changes in the organs constituting the kinetic chain; why the same pathologic changes result from various forms of activation of the kinetic system. In this hypothesis we find a reason why cardiovascular disease may be caused by chronic infection, by auto-intoxication, by overwork, or by emotional excitation. We now see that the reason why we find so much difficulty in differentiating the numerous acute infections from each other is because they play upon the same kinetic chain. Our postulate harmonizes the pathologic democracy of the kinetic organs, for it explains not only why, in many diseases, the pathologic changes in these organs are identical, but why the same changes are seen as the result of emotional strain and overwork. We can thus understand how either emotional strain or acute or chronic infection may cause either exophthalmic goiter or cardiovascular disease; how chronic intestinal stasis with the resultant absorption of toxins may cause cardiovascular disease, neurasthenia, or goiter. Here is found an explanation of the phenomena of shock, whether the shock be the result of toxins, of infection, of foreign proteins, of anaphylaxis, of psychic stimuli, or of a surgical operation with its combination of both psychic and traumatic elements.
This conception of the kinetic system has stood a crucial test by making possible the shockless operation. It has offered a plausible explanation of the cause and the treatment of Graves’ disease. Will the kinetic theory stand also the clinical test of controlling that protean disease bred in the midst of the stress of our present-day life? Present-day life, in which one must ever have one hand on the sword and the other on the throttle, is a constant stimulus of the kinetic system. The force of these kinetic stimuli may be lessened at the cerebral link by intelligent control–a protective control is empirically attained by many of the most successful men. The force of the kinetic stimuli may be broken at the thyroid link by dividing the nerve supply, reducing the blood supply, or by partial excision; or if the adrenals feel the strain, the stimulating force may be broken by dividing their nerve supply, reducing the blood supply, or by partial excision. No theory is worth more than its yield in practice, but already we have the shockless operation, the surgical treatment of Graves’ disease, and the control of shock and of the acute infections by overwhelming morphinization (Figs. 62, 72, and 73).
Conclusions
To become adapted to their environment animals are transformers of energy. This adaptation to environment is made by means of a system of organs evolved for the purpose of converting potential energy into heat and motion. The principal organs and tissues of this system are the brain, the adrenals, the thyroid, the muscles, and the liver. Each is a vital link, each plays its particular role, and one cannot compensate for the other. A change in any link of the kinetic chain modifies proportionately the entire kinetic system which is no stronger than its weakest link.
In this conception we find a possible explanation of many diseases one which may point the way to new and more effective therapeutic measures than those now at our command.
ALKALESCENCE, ACIDITY, ANESTHESIA–A THEORY OF ANESTHESIA[*]
[*] Paper delivered before the Virginia Medical Association, Washington, D. C., October 29, 1914.
Alkalis and bases compose the greater part of the food of man and animals, the blood in both man and animals under normal conditions being slightly alkaline or rather potentially alkaline; that is, although in circulating blood the concentration of the OH-ions– upon which the degree of alkalinity depends–is but little more than in distilled water, yet blood has the power of neutralizing a considerable amount of acid (Starling, Wells). At the time of death, whatever its cause, the concentration of H-ions in the blood increases,– the concentration of H-ions being a measure of acidity,–that is, the potential or actual alkalinity decreases and the blood becomes actually neutral or acid.
To determine what conditions tend to diminish the normal alkalinity of the blood, many observations were made for me in my laboratory by Dr. M. L. Menten to determine by electric measurements the H-ion concentration of the blood under certain pathologic and physiologic conditions.
As a result of these researches we are able to state that the H-ion concentration of the blood–its acidity–is increased by excessive muscular activity; excessive emotional excitation; surgical shock; in the late stages of infection; by asphyxia; by strychnin convulsions; by inhalation anesthetics; after excision of the pancreas, and in the late stages of life after excision of the liver and excision of the adrenals. Morphin and decapitation cause no change in the H-ion concentration. Ether, nitrous oxid, and alcohol produce an increased acidity of the blood which is proportional to the depth of anesthesia.
Many of the cases studied were near death, as would be expected, since it is well known that a certain degree of acidity is incompatible with life.
Since alkalis and bases preponderate in ingested food; since alkalinity of the blood is diminished by bodily activity; and since at the point of death the blood is always acid, we may infer that some mechanism or mechanisms of the body were evolved for the purpose of changing bases into acids that thus energy might be liberated.
These observations lead naturally to the question, May not acidity of itself be the actual final cause of death? We believe that it may be so from the facts that–(1) The intravenous injection of certain acids causes death quickly, but that convulsions do not occur, since the voluntary muscles lose their power of contraction; and (2) the intravenous injection of acids causes extensive histologic changes in the brain, the adrenals, and the liver which resemble the changes invariably caused by activation of the kinetic system (Figs. 74 and 75). In view of these facts may we not find that anesthesia and many instances of unconsciousness are merely phenomena of acidity?
As has been stated already, we have found that the H-ion concentration of the blood–its acidity–is increased by alcohol, by ether, and by nitrous oxid. In addition our tests have shown that under ether the increase of the H-ion concentration–acidity–is more gradual than under nitrous oxid, an observation which accords well with the fact that nitrous oxid more quickly induces anesthesia than does ether.
Further striking testimony in favor of the hypothesis that the production of acidity by inhalation anesthetics is the method by which anesthesia itself is produced is found in the fact that although lethal doses of acid cause muscular paralysis, yet this paralysis may be mitigated by adrenalin–which is alkaline. This observation may explain in part the remarkable success of the method of resuscitation devised by me, in which animals “killed” by anesthetics and asphyxia are revived by the use of adrenalin.
In animals under inhalation anesthesia Williams found that no nerve-current could be detected by the Einthoven string galvanometer, a fact which might be explained by postulating that nerve-currents can flow from the brain to the muscles and glands only when there is a difference of potential. Any variation from the normal alkalinity of the body must change the difference in potential. Since the nerve-currents in animals under anesthesia are not demonstrable by any apparatus at our command, and since anesthesia produces acidity, then we may infer that acidity reduces the difference in potential. As long as there is life, a galvanometer of sufficient delicacy would perforce detect, a nerve-current until the acidity increased to such a point as to reduce the difference in potential to zero– the point of death. If at this point a suitable alkali– adrenalin solution–can be introduced quickly enough, the vital difference in potential may be restored and the life processes will be renewed. Bearing especially on this point is the fact that if adrenalin in sufficient quantities be administered simultaneously with an acid, it will not only prevent the fall in blood-pressure usually caused by the acid, but will also prevent the histologic changes in the brain, adrenals, and liver which are usually caused by the intravenous injection of acids.
This hypothesis regarding the cause of anesthesia and unconsciousness explains and harmonizes many facts. It explains how asphyxia, overwhelming emotion, and excessive muscular exertion, by causing acidity, may produce unconsciousness. It explains the acidosis which results from starvation, from uremia, from diabetes, from Bright’s disease, and supplies a reason for the use of intravenous infusions of sodium bicarbonate to overcome the coma of diabetes and uremia (Fig. 76). It may explain the quick death from chloroform and nitrous oxid; and may perhaps show why unconsciousness is so commonly the immediate precursor of death.
One of the most noticeable immediate effects of the administration of an inhalation anesthetic is a marked increase in the rapidity and force of the respiration. The respiratory center has evidently been evolved to act with an increase of vigor which is proportional– within certain limits–to the increase in the H-ion concentration, whereas the centers governing the voluntary muscles are inhibited. In this antithetic reaction of the higher cortical centers and the lower centers in the medulla to acidity we find a remarkable adaptation which prevents the animal from killing itself by the further increase in acidity which would be produced by muscular activity. That is, as the acidity produced by muscular action increases and threatens life, the respiratory action, by which carbon dioxid is eliminated and oxygen supplied, is increased, while the driving power of the brain, which produces acidity, is diminished or even inhibited entirely; that is, the state of unconsciousness or anesthesia is reached. We conclude first that, without this life-saving regulation, animals under stress would inevitably commit suicide; and, second, that it is probable that the remarkable phenomenon of anesthesia– the coincident existence of unconsciousness and life–is due to this antithetic action of the cortex and the medulla.
In the human, as in the animal, the degree of acidity parallels the depth of inhalation anesthesia.
Within a few seconds after beginning nitrous oxid anesthesia the acidity of the blood is increased. This rapid acidulation is synchronous with almost instantaneous unconsciousness and increased respiration. If the oxygen in the inhaled mixture be increased, a decrease in acidity is again synchronous with lighter anesthesia and a decrease in the respiratory rate.
If these premises be sound, we are justified in asserting that the state of anesthesia is due to an induced acidity of the blood. If the acidity is slight, then the anesthesia is slight and the force of the nerve impulses is lessened, but the patient is still conscious of them. As the acidity increases associative memory is lost, and the patient is said to be unconscious: the centers governing the voluntary muscles are not inhibited, however, and cutting the skin causes movements. If the acidity is further increased, there is loss of muscular tone and even the strong contact ceptor stimuli of a surgical operation do not cause any muscular response, and, finally, the acidity may be increased to the point at which the respiratory and circulatory centers can no longer respond by increased effort, and anesthetic death– that is, ACID death–follows.
Certain clinical phenomena are clarified by this theory and serve to substantiate it. For example, it is well known that inhalation anesthesia precipitates the impending acidosis which results from starvation, from extreme Graves’ disease, from great exhaustion, from surgical shock, and from hemorrhage, and which is present when death from any cause is imminent.
We see, therefore, that anesthesia is made possible, first, by the fact that inhalation anesthetics cause acidity, and, second, by the antithetic adaptation of the higher centers in the brain and of the centers governing respiration and circulation.
In deep contrast to the action of inhalation anesthetics is that of narcotics. Deep narcotization with morphin and scopolamin is induced slowly; the respiratory and pulse-rate are progressively lessened– and there is no acidity.
By our researches we have established in what consists the generic difference between inhalation anesthetics and narcotics. In our experiments no increase in the H-ion concentration was produced by morphin or by scopolamin, no matter how deep the narcotization. In animals already narcotized by morphin the production of acid by any of the acid-producing stimuli was delayed or prevented. On the other hand, in animals in which an acidity had already been produced by ether, by shock, by anger, or by fear, the later administration of morphin delayed or inhibited entirely the neutralization of the acidity. In other words, morphin interferes with the normal mechanism by which acidity is neutralized possibly because its inhibiting action on the respiratory center is sufficient to overcome the stimulating action of acidity on that center, for, as we have stated, the neutralization of acidity is in large measure accomplished by the increased respiration induced by the acidity itself.
SUMMARY
Acidity inhibits the functions of the cerebral cortex, but stimulates those of the medulla. This antithetic reaction to the stimulus of increased H-ion concentration is an adaptation to prevent animals from committing suicide by over-activity, for the mechanism for the initiation and control of the transformation of energy is in the higher centers of the brain, while an essential part of the mechanism for the neutralization of acidity–the centers governing circulation and respiration– is in the medulla. This explains many clinical phenomena– why excessive acidity causes paralysis, why there is great thirst after inhalation anesthesia, after excessive muscular activity, excessive emotion–after all those activities which we have found to be acid-producing, for water, like air, neutralizes acids. The excessive use of alcohol, anesthetics, excessive work, intense emotion, all produce lesions of the kidney and of the liver. The explanation is found in the fact that all these stimuli increase the acidity of the blood. and that, if long continued, the neutralizing mechanism must be broken down and so the end-products of metabolism are insufficiently prepared for elimination.
In view of these considerations we may well conclude that the maintenance of the normal potential alkalinity of the blood is to be estimated as the keystone of the foundation of life itself.
INDEX
ABDOMEN, diseases of, phylogenetic association and, 44 Acidity, 227 Adaptive energy, 176 variation in rate of energy discharge, 177 Adrenalin, Cannon’s test for, 134, 196 injection of, changes in brain-cells from, 186 Adrenals, 196 brain and, relation of, 1.98 diseases of, effect of, on output of energy, 216 functional study of, 196 histologic study of, 198 Alcohol, changes in brain-cells from, 116 Alkalescence, 227 Anemia, pain of, 77 Anesthesia, 2, 227 anoci-association and, differentiation, 34 effect of trauma under, upon brain that remains awake, 3 inhalation, cause of exhaustion of brain-cells as result of trauma under, 8 theory of, 227 Anger, 63, 70 Anoci-association, 34 anesthesia and, differentiation, 34 Graves’ disease and, 36 prevention of shock by application of principle of, 36 Aristotle, 127 Asher, :37 Associational centers, dulled, 47 Austin, 2, 55, 173
BASS, 159 Beebe, 213 Benedict, 212 Biologic consideration of adaptive variation in amounts of energy stored in various animals, 176 Brain, adrenals and, relation of, 198 diseases of, effect of, on output of energy, 216 effect of trauma under anesthesia oil, 3 functions, physical state of brain-cells and, relation between, 111 influence of fear on, 64 Brain-cells, cause of exhaustion of as result of trauma under inhalation anesthesia, 8 changes in, from alcohol, 116 from drugs, 113 from fatigue, 112 from fear, 112 from hemorrhage, 113 from injection of adrenalin, 186 from iodoform, 116 from strychnin, 113 in Graves’ disease, 116 in infections, 116 in insanity, 120 in insomnia, 119 histologic changes in, in relation to maintenance of consciousness and to production of emotions, muscular activity, and fever, 182 physical state, brain functions and, relation between, 111
CANNON, 57, 64, 68, 73, 133, 138, 196, 202 Cannon’s test for adrenalin, 134, 196 Cells, brain-, cause of exhaustion of, as result of trauma under inhalation anesthesia, 8 changes in, from alcohol, 116 from drugs, 113 from fatigue, 112 from fear, 112 from hemorrhage, 113 from injection of adrenalin, 186 from iodoform, 116 from strychnin, 113 in Graves’ disease, 116 in infections, 116 in insanity, 120 in insomnia, 119 histologic changes in, in relation to maintenance of consciousness and to production of emotions, muscular activity, and fever, 182 physical state, brain functions and, relation between, Ill Chemical noci-association in infections, 48 Cold pain, 83 sweat, 27 Contact pain, special, 78 Crying, 90 in exophthalmic goiter, 106
DARWIN, 12, 26, 30, 91, 127, 153 on phenomena of fear, 26 Disease, mechanistic theory of, 157 Distance receptors, discharge of energy through stimulation of, 25 Dog, spinal, 4 Dolley, 2, 10 Drugs, changes in brain-cells from, 113
ELIOT, 1 Elliott, 202 Energy, adaptive, 176 Energy, discharge, rate of, adaptive variation in, 177 nervous, cause of discharge of, 12 as result of trauma under inhalation anesthesia, 12 discharge of, role of summation in, 30 through representation of injury, 25 through stimulation of distance receptors, 25 psychic discharge, 25 output of, effect of diseases of adrenals on, 216 of brain on, 216 of liver on, 216 of muscles on, 216 of thyroid on, 217 rate of out put, influences that cause variation in, 177 Environment, 128, 130 Evacuation pain, 77 Exophthalmic goiter, 66 crying in, 106 fear and, resemblance between, 68 laughing in, 106
FATIGUE, changes in brain-cells from, 112 Fear, 26, 52, 55 changes in brain-cells from, 112 Darwin on phenomena of, 26 Graves’ disease and, resemblance between, 68 influence of, on brain, 61 phenomena of, 56 Fly-trap, Venus’, 151 Frankel, 68 Frazier, 82 Functional study of adrenals, 196
GOITER, exophthalmic, 66 crying in, 106 Goiter, exophthalmic, fear and, resemblance between, 68 laughter in, 106 Graves’ disease, 66 anoci-association and, 36 changes in brain-cells in, 116 crying in, 106 fear and, resemblance between, 68 laughter in, 106
HARVEY, 1,57 Headache, 80 Heat pain, 77 production in infections, purpose and mechanism, 180 Hemorrhage, changes in brain-cells from, 113 Hippocrates, 127 Histologic changes in liver, 205 study of adrenals, 198 Hitchings, 173 Hodge, 10 Hornaday, 26 Hydrogen ion concentration in activation of kinetic system, 217 Hyperthyroidism, 42
INFECTIONS, changes in brain-Cells in, 116 chemical noci-association in, 48 heat production in, purpose and mechanism, 180 pain of, 79 Inhalation anesthesia, cause of exhaustion of brain-cells as result of trauma under, 8 trauma under, cause of discharge of nervous energy as result of, 12 Insanity, changes in brain-cells in, 120 Insomnia, changes in brain-cells in, 119 effect of, 205
Iodoform, changes in brain-cells from, 116
KINETIC diseases, 219 reaction, 93 system, 173
LABOR pains, 79 Laughter, 90 causes of, 91 in exophthalmic goiter, 106 Law, Sherrington’s, 24 Light pain, 77 Liver, diseases of, effect of, on output of energy, 216 histologic changes in, 205 Livingstone, 148 Lower, 42
MALARIA, 159 McKenzie, 162 Mechanistic theory of disease, 157 view of psychology, 127 Medical problems, phylogenetic association in relation to, 1 Menten, 2, 55, 173, 218, 227 Muscles, diseases of, effect of, on output of energy, 216
NAGGING, 46 Nausea pains, 78 Nervous energy, cause of discharge of, 12 as result of trauma under inhalation anesthesia, 12 discharge of, role of summation in, 30 through representation of injury, 25 through stimulation of distance receptors, 25 psychic discharge, 25 Neurasthenia, sexual, 43 Neuroses, postoperative, 46 traumatic, 46 Noci-association, chemical, in infections, 48 Nociceptors, 14 diseases and injuries of regions not endowed with, 47
PAIN, 77, 107, 144, 158 cold, 83 contact, special, 78 evacuation, 77 heat, 77 labor, 78 light, 77 nausea, 78 of anemia, 77 of infection, 79 pleasure, 78 post-operative, 89 site of, 83 traumatic, 89 Personality, 47 Phylogenetic association, diseases of abdomen and, 44 in relation to certain medical problems, 1 to emotions, 55 Pleasure pains, 78 Postoperative neuroses, 46 pain, 89 Propagation of species, 152 Psychic discharge of energy, 25 Psychology, mechanistic view, 127
REACTION, kinetic, 93 Receptors, distance, discharge of energy through stimulation of, 25 sexual, 53 ticklish, 19
SELF-PRESERVATION, 152 Sexual neurasthenia, 43 Sexual receptors, 53 Sherrington, 12, 13, 14, 24, 25, 48, 52, 132, 136, 158 Sherrington’s law, 24 Shock, prevention of, by application of principle of anoci-association, 36 Sloan, 2, 14, .55, 173 Spinal dog, 4 Starling, 195, 227 Strychnin, changes in brain-cells from, 113 Summation, role of, in discharge of nervous energy, 30 Sweat, cold, 27
TEST, Cannon’s, for adrenalin, 134, 196 Thyroid gland, 213 diseases of, effect of, on output of energy, 217 Ticklish receptors, 19 Trauma, cause of exhaustion of brain-cells as result of, under inhalation anesthesia, 8 effect of, under anesthesia, upon brain that remains awake, 3 under inhalation anesthesia, cause of discharge of nervous energy as result of, 12 Traumatic neuroses, 46 pain, 89
VAUGHAN, 180 Venus’ fly-trap, 149, 151
WEEPING, 90 Welch, 1 Wells, 227 Williams, 231 Worry, 74