1. The Bile is secreted by the liver. This gland weighs about four pounds, and is the largest in the body. It is located on the right side, below the diaphragm. The bile is of a dark, golden color, and bitter taste. About three pounds are secreted per day. When not needed for digestion, it is stored in the gall cyst. [Footnote: A gall bladder can be obtained from a butcher, and the contents kept in a bottle for examination.] Its action on the food, though not fully understood, is necessary to life. [Footnote: The bile is produced, unlike all the other animal secretions, from venous blood; that is, the already contaminated blood of the portal vein. Its complete suppression produces symptoms of poisoning analogous to those which follow the stoppage of respiration, and the patient dies, usually in a comatose condition, at the end of ten or twelve days.—DALTON. The alkaline bile neutralizes the acid contents of the stomach as they flow into the duodenum, and thus prepares the way for the pancreatic juice. It has also a slight emulsifying power (note, p. 167).]
2. The Pancreatic Juice is a secretion of the pancreas, or "sweetbread"—a gland nearly as large as the hand, lying behind the stomach. It is alkaline, and contains a ferment called trypsin. This juice has the power of changing starch to sugar. Its main work, however, is in breaking up the globules of fat into myriads of minute particles, that mix freely with water, and remain suspended in it like butter in new milk. The whole mass now assumes a milky look, whence it is termed chyle (kile) and passes on to the small intestine. [Footnote: It is curious to observe that while the gastric juice is decidedly acid, the fluids with which the food next comes into contact are alkaline. It is thus submitted to the operation alternately of alkaline, acid, and again of alkaline secretions. In the herbivora there is also a second acid juice. The reason of these alternations is not known, but it can hardly be doubted that they serve to make the digestion of the food more perfect. And although the solvent power of the gastric juice is placed in abeyance when its acidity is neutralized by the alkaline fluids, yet it appears to be the case here, as in respect to the saliva, that effects are produced by the mixture of the various secretions which are poured together into the digestive tube, that would not result from either alone.—HINTON.]
3. The Small Intestine is an intricately folded tube, about twenty feet long, and from an inch to an inch and one half in diameter. As the chyle passes through this tortuous channel, it receives along the entire route secretions which seem to combine the action of all the previous ones—starch, fat, and albumen being equally affected.
IV. ABSORPTION is performed in two ways, by the veins, and the lacteals. (1.) The veins in the stomach [Footnote: The veins and the lacteals are separated from the food by a thin, moist membrane, through the pores of which the fluid food rapidly passes, in accordance with a beautiful law ("Popular Physics," p. 53) called the Osmose of liquids. If two liquids of different densities are separated by an animal membrane, they will mix with considerable force. There is a similar law regulating the interchange of gases through a porous partition, in obedience to which the carbonic acid of the blood, and the oxygen of the lungs, are exchanged through the thin membrane of the air cells.] immediately begin to take up the water, salt, grape sugar, and other substances that need no special preparation. The starch and the albuminous bodies are also absorbed as they are properly digested, and this process continues along the whole length of the alimentary canal. In the small intestine, there is a multitude of tiny projections (villi) from the folds of the mucous membrane, more than seven thousand to the square inch, giving it a soft, velvety look. These little rootlets, reaching out into the milky fluid, drink into their minute blood vessels the nutritious part of every sort of food. (2.)The lacteals [Footnote: From lac, milk, because of the milky look given to their contents by the chyle.] (p. 126), a set of vessels starting in the villi side by side with the veins, absorb the principal part of the fat. They convey the chyle through the lymphatics and the thoracic duct (Fig. 43) to the veins, and so within the sweep of the circulation.
The Portal Vein [Footnote: So named because it enters the liver by a sort of gateway.] carries to the liver the food absorbed by the veins of the stomach and the villi of the intestines. On the way, it is greatly modified by the action of the blood itself. In the cells of the liver, it undergoes as mysterious a process as that performed by the lymphatic glands, and is then cast into the circulation. [Footnote: In these cells, the sugar is changed into a kind of starch called glycogen. This is insoluble, and so is stored up in the liver, and even in the substance of the muscles, until it is needed by the body, when it is once more converted into soluble sugar and taken up by the circulation. The liver also changes the waste and surplus albuminous matter into bile, and into urea and uric acid—the forms in which nitrogenized waste is excreted by the kidneys.] The food, potent with force, is now buried in that river of life from which the body springs momentarily afresh.
THE COMPLEXITY of the process of digestion, as compared with the simplicity of respiration and circulation, is very marked. The mechanical operation of mastication; the lubrication of the food by mucus; the provision for the security of the respiratory organs; the grasping by the muscles of the throat; the churning movement of the stomach; the guardianship of the pylorus; the timely introduction by safe and protected channels of the saliva, the gastric juice, the bile, the pancreatic juice, and the intestinal fluids, each with its special adaptation; the curious peristaltic motion of the intestines; the twofold absorption by the veins and the lacteals; the final transformation in the lymphatics, the portal vein, and the liver,—all these present a complexity of detail, the necessity of which can be explained only when we reflect upon the variety of the substances we use for food, and the importance of its thorough preparation before it is allowed to enter the blood.
THE LENGTH OF TIME REQUIRED for digesting a full meal is from two to four hours. It varies with the kind of food, state of the system, perfection of mastication, etc. In the celebrated observations made upon Alexis St. Martin [Footnote: In 1822, Alexis St. Martin, a Canadian in the employ of the American Fur Company, was accidentally shot in the left side. Two years after, the wound was entirely healed, leaving, however, an opening about two and a half inches in circumference into the stomach. Through this the mucous membrane protruded, forming a kind of valve which prevented the discharge of food, but could be readily depressed by the finger, thus exposing the interior. For several years he was under the care of Dr. Beaumont, a skillful physician, who experimented upon him by giving various kinds of food, and watching their digestion through this opening. By means of these observations, and others performed on Katherine Kutt, a woman who had a similar aperture in the stomach, we have very important information as to the digestibility of different kinds of food.] by Dr. Beaumont, his stomach was found empty in two and a half hours after a meal of roast turkey, potatoes, and bread. Pigs' feet and boiled rice were disposed of in an hour. Fresh, sweet apples took one and a half hours; boiled milk, two hours; and unboiled, a quarter of an hour longer. In eggs, which occupied the same time, the case was reversed,—raw ones being digested sooner than cooked. Roast beef and mutton required three and three and a quarter hours respectively; veal, salt beef, and broiled chicken remained for four hours; and roast pork enjoyed the bad preeminence of needing five and a quarter hours.
VALUE OF THE DIFFERENT KINDS OF FOOD.—Beef and Mutton possess the greatest nutritive value of any of the meats. Lamb is less strengthening, but more delicate. Like the young of all animals, it should be thoroughly cooked, and at a high temperature, properly to develop its delicious flavor. Pork has much carbon. It sometimes contains a parasite called trichina, which may be transferred to the human system, producing disease and often death. The only preventive is thorough cooking. Fish is more watery than flesh, and many find it difficult of digestion. Like meat, it loses its mineral constituents and natural juices when salted, and is much less nourishing. Oysters are highly nutritious, but are more easily assimilated when raw than when cooked. Milk is a model food, as it contains albumen, starch, fat, and mineral matter. No other single substance can sustain life for so long a time. Cheese is very nourishing—one pound being equal in value to two of meat, but it is not adapted to a weak stomach. (See p. 322.) Eggs are most easily digested when the white is barely coagulated and the yolk is unchanged. Bread [Footnote: Very fresh bread, warm biscuit, etc., are condensed by mastication into a pasty mass that is not easily penetrated by the gastric juice, and hence they are not healthful. In Germany bread is not allowed to be sold at the baker's till it is twenty-four hours old—a wise provision for those who have not strength to resist temptation. This rule of eating may well be adopted by every one who cares more for his health than for a gratification of his appetite.] should be made of unbolted flour. The bran of wheat furnishes the mineral matter we need in our bones and teeth, gives the bulk so essential to the proper distension of the organs, and by its roughness gently stimulates them to action. Corn is rich in fat. It contains, however, more indigestible matter than any other grain, except oats, and is less nutritious than wheat. [Footnote: Persons unaccustomed to the use of corn find it liable to produce derangement of the digestive organs. This was made fearfully apparent in the prisons of Andersonville during the late civil war. The vegetable food of the Federal prisoners had hitherto been chiefly wheat bread and potatoes—the corn bread so extensively used at the South being quite new to most of them as a constant article of diet. It soon became not only loathsome, but productive of serious diseases. On the other hand, it was the principal article in the rations of the Confederate soldiers, to whom habit made it a nutritious and wholesome form of food, as was shown by their endurance.—FLINT, Physiology of Man, Vol. II, page 41.] The Potato is two thirds water,—the rest being mainly starch. Ripe Fruits, and those vegetables usually eaten raw, dilute the more concentrated food, and also supply the blood with acids, which are cooling in summer, and useful, perhaps, in assimilation.
THE STIMULANTS.—Coffee is about half nitrogen, and the rest fatty, saccharine, and mineral substances. It is, therefore, of much nutritive value, especially when taken with milk and sugar. Its peculiar stimulating property is due to a principle called caffeine. Its aroma is developed by browning, but destroyed by burning. No other substance so soon relieves the sense of fatigue. [Footnote: In the late civil war, the first desire of the soldiers upon halting after a wearisome march, was to make a cup of coffee. This was taken without milk, and often without sugar, yet was always welcome.] Taken in moderation, it clears the intellect, tranquilizes the nerves, and usually leaves no unpleasant reaction. It serves also as a kind of negative food, since it retards the process of waste.
In some cases, however, it produces a rush of blood to the head, and should be at once discarded. At the close of a full meal it hinders digestion, and at night produces wakefulness. In youth, when the vital powers are strong, and the functions of nature prompt in rallying from fatigue, it is not needed, and may be injurious in stimulating a sensitive organization.
Tea possesses an active principle called theine. When used moderately, its effects are similar to those of coffee, except that it exerts an astringent action. It contains tannin, which, if the tea is strong, coagulates the albumen of the food—tans it—and thus delays digestion. In excess, tea causes nervous tremor, disturbed sleep, palpitation of the heart, and indigestion. [Footnote: Tea and coffee should be made with, boiling water, but should not be boiled afterward. During the "steeping" process, so customary in this country, the volatile aroma is lost and a bitter principle extracted. In both England and China it is usual to infuse tea directly in the urn from which it is to be drawn. The tannin in tea is shown when a drop falls on a knife blade. The black spot is a tannate of iron—a compound of the acid in the tea and the metal.] (See p. 322.)
Chocolate contains much fat, and also nitrogenous matter resembling albumen. Its active principle, theobromine, [Footnote: It is said that Linnæus, the great botanist, was so fond of chocolate that he named the cocoa tree "Theobroma," the food of the gods.] has some of the properties of caffeine and theine.
THE COOKING OF FOOD breaks the little cells, and softens the fibers of which it is composed. In broiling or roasting meat, it should be exposed to a strong heat at once, in order to coagulate the albumen upon the outside, and thus prevent the escape of the nutritious juices. The cooking may then be finished at a lower temperature. The same principle applies to boiling meat. In making soups, on the contrary, the heat should be applied slowly, and should reach the boiling point for only a few moments at the close. This prevents the coagulation of the albumen. Frying is an unhealthful mode of cooking food, as thereby the fat becomes partially disorganized.
RAPID EATING produces many evil results. 1. There is not enough saliva mixed with the food; 2. The coarse pieces resist the action of the digestive fluids; 3. The food is washed down with drinks that dilute the gastric juice, and hinder its work; 4. We do not appreciate the quantity we eat until the stomach is overloaded; 5. Failing to get the taste of our food, we think it insipid, and hence use condiments that overstimulate the digestive organs. In these various ways the appetite becomes depraved, the stomach vexed, the system overworked, and the foundation of dyspepsia is laid. [Footnote: When one is compelled to eat in a hurry, as at a railway station, he would do well to confine himself principally to meat; and to dilute this concentrated food with fruit, crackers, etc., taken afterward more leisurely.] (See p. 324.)
THE QUANTITY AND QUALITY OF FOOD required vary with the age and habits of each individual. The diet of a child [Footnote: In youth, repair exceeds waste; hence the body grows rapidly, and the form is plump. In middle life, repair and waste equal each other, and growth ceases. In old age, waste exceeds repair; hence the powers are enfeebled and the skin lies in wrinkles on the shrunken form.] should be largely vegetable, and more abundant than that of an aged person. A sedentary occupation necessitates less food than an outdoor life. One accustomed to manual labor, on entering school, should practice self-denial until his system becomes fitted to the new order of things. He should not, however, fall into the opposite error. We read of great men who have lived on bread and water, and the conscientious student sometimes thinks that, to be great, he, too, must starve himself. [Footnote: As Dr. Holland well remarks, the dispensation of sawdust has passed away. If we desire a horse to win the race, we must give him plenty of oats.] On the contrary, many of the greatest workers are the greatest eaters. A powerful engine needs a corresponding furnace. Only, we should be careful not to use more fuel than is needed to run the machine. (See p. 325.)
The season should modify our diet. In winter, we need highly carbonaceous food, plenty of meat, fat, etc.; but in summer we should temper the heat in our corporeal stoves with fruits and vegetables.
The climate also has its necessities. The inhabitants of the frigid north have an almost insatiable longing for fat. [Footnote: Dr. Hayes, the arctic explorer, says, that the daily ration of the Esquimaux was from twelve to fifteen pounds of meat, one third being fat. On one occasion, he saw a man eat ten pounds of walrus flesh and blubber at a single meal. The low temperature had a remarkable effect on the members of his own party, and some of them were in the habit of drinking the contents of the oil kettle with evident relish. Other travelers narrate the most incredible stories of the voracity of the inhabitants of arctic regions. Saritcheff, a Russian admiral, tells of a man who in his presence ate, at a meal, a mess of twenty-eight pounds of boiled rice and butter, although he had already partaken of his breakfast. Captain Cochrane further adds, in narrating this statement, that he has himself seen three of the savages consume a reindeer at a sitting.] Thus, in 1812, when the Allies entered Paris, the Cossacks drank all the oil from the lamps, and left the streets in darkness. In tropical regions, a low, unstimulating diet of fruits forms the chief dependence. [Footnote: A natural appetite for a particular kind of food is an expression not only of desire, but of fitness. Thus the craving of childhood for sugar indicates a need of the system. It is questionable how far it is proper to force or persuade one to eat that which he disrelishes, or his stomach loathes. Life within is linked with life without. Each organ requires its peculiar nutriment, and there is often a peculiar influence demanded of which we can have no notice except by natural instinct. Yet, as we are creatures of habit and impulse, we need common sense and good judgment to correct the too often wayward promptings of an artificial craving.]
WHEN FOOD SHOULD BE TAKEN.—On taking food, the blood sets at once to the alimentary canal, and the energies are fixed upon the proper performance of this work. We should not, therefore, undertake hard study, labor, or exercise directly after a hearty meal. We should give the stomach at least half an hour. He who toils with brain or muscle, and thus centers the blood in any particular organ, before eating should allow time for the circulation to become equalized. There should be an interval of four to five hours between our regular meals, and there should be no lunching between times. With young children, where the vital processes are more rapid, less time may intervene. As a general rule, nothing should be eaten within two or three hours of retiring. (See p 336.)
HOW FOOD SHOULD BE TAKEN.—A good laugh is the best of sauces. The mealtime should be the happiest hour of the day. Care and grief are the bitter foes of digestion. A cheerful face and a light heart are friends to long life, and nowhere do they serve us better than at the table. God designed that we should enjoy eating, and that, having stopped before satiety was reached, we should have the satisfaction always attendant on a good work well done.
NEED OF VARIETY.—Careful investigations have shown that any one kind of food, however nutritious in itself, fails after a time to preserve the highest working power of the body. Our appetite palls when we confine our diet to a regular routine. Nature demands variety, and she has furnished the means of gratifying it. [Footnote: She opens her hand, and pours forth to man the treasures of every land and every sea, because she would give to him a wide and vigorous life, participant of all variety. For him the cornfields wave their golden grain—wheat, rye, oats, maize, or rice, each different, but alike sufficing. Freely for him the palm, the date, the banana, the breadfruit tree, the pine, spread out a harvest on the air; and pleasant apple, plum, or peach solicit his ready hand. Beneath his foot lie stored the starch of the potato, the gluten of the turnip, the sugar of the beet; while all the intermediate space is rich with juicy herbs.
Nature bids him eat and be merry; adding to his feast the solid flesh of bird, and beast, and fish, prepared as victims for the sacrifice: firm muscle to make strong the arm of toil, in the industrious temperate zone; and massive ribs of fat to kindle inward fires for the sad dwellers under arctic skies.—Health and its Conditions.—HINTON.]
THE WONDERS OF DIGESTION.—We can understand much of the process of digestion. We can look into the stomach and trace its various steps. Indeed, the chemist can reproduce in his laboratory many of the operations; "a step further," as Fontenelle has said, "and he would surprise nature in the very act." Just here, when he seems so successful, he is compelled to pause. At the threshold of life the wisest physiologist reverently admires, wonders, and worships.
How strange is this transformation of food to flesh! We make a meal of meat, vegetables, and drink. Ground by the teeth, mixed by the stomach, dissolved by the digestive fluids, it is swept through the body. Each organ, as it passes, snatches its particular food. Within the cells of the tissues [Footnote: As the body is composed of individual organs, and each organ of separate tissues, so each tissue is made up of minute cells. Each cell is a little world by itself, too small to be seen by the naked eye, but open to the microscope. It has its own form and constitution as much as a special organ in the body. It absorbs from the blood such food as suits its purposes. Moreover, the number of cells in an organ is as constant as the number of organs. As the organs expand with the growth of the body, so the cells of each tissue enlarge, but shrink again with age and the decline of life. Life begins and ends in a cell.—See Appletons' Cyclopedia, Art. "Absorption."] it is transformed into the soft, sensitive brain, or the hard, callous bone; into briny tears, or bland saliva, or acrid perspiration; bile for digestion, oil for the hair, nails for the fingers, and flesh for the cheek.
Within us is an Almighty Architect, who superintends a thousand builders, which make in a way past all human comprehension, here a fiber of a muscle, there a filament of a nerve; here constructing a bone, there uniting a tendon,—fashioning each with scrupulous care and unerring nicety. [Footnote: See COOKE'S Religion and Chemistry, page 236.] So, without sound of builder or stroke of hammer, goes up, day by day, the body—the glorious temple of the soul.
DISEASES ETC.—1. Dyspepsia, or indigestion of food, is generally caused by an overtaxing of the digestive organs. Too much food is used, and the entire system is burdened by the excess. Meals are taken at irregular hours, when the fluids are not ready. A hearty supper is eaten when the body, wearied with the day's labor, demands rest. The appetite craves no food when the digestion is enfeebled, but stimulants and condiments excite it, and the unwilling organs are oppressed by that which they can not properly manage.
Strong tea, alcoholic drinks, and tobacco derange the alimentary function.
Too great variety of dishes, rich food, tempting flavors,—all lead to an overloading of the stomach. This patient, long-suffering member at last wears out. Pain, discomfort, diseases of the digestive organs, and insufficient nutrition are the penalties of violated laws. (See p. 328.)
2. The Mumps are an inflammation of the parotid and submaxillary glands (see p. 159). The disease is generally epidemic, and is believed to be contagious; the patient should therefore be carefully secluded for the sake of others as well as himself. The swelling may be allowed to take its course. Relief from pain is often experienced by applying flannels wrung out of hot water. Great care should be used not to check the inflammation, and, on first going out after recovery, not to take cold.
ALCOHOLIC DRINKS AND NARCOTICS.
1. ALCOHOL (Continued from p. 147).
RELATION OF ALCOHOL TO THE DIGESTIVE ORGANS.—Is Alcohol a Food? To answer this question, let us make a comparison. If you receive into your stomach a piece of bread or beef, Nature welcomes its presence. The juices of the system at once take hold of it, dissolve it, and transform it for the uses of the body. A million tiny fingers (lacteals and veins) reach out to grasp it, work it over, and carry it into the circulation. The blood bears it onward wherever it is needed to mend or to build "The house you live in." Soon, it is no longer bread or beef; it is flesh on your arm; its chemical energy is imparted to you, and it becomes your strength.
If, on the other hand, you take into your stomach a little alcohol, it receives no such welcome. Nature treats it as a poison, and seeks to rid herself of the intruder as soon as possible. [Footnote: Food is digested, alcohol is not. Food warms the blood, directly or indirectly; alcohol lowers the temperature. Food nourishes the body, in the sense of assimilating itself to the tissues; alcohol does not. Food makes blood; alcohol never does anything more innocent than mixing with it. Food feeds the blood cells; alcohol destroys them. Food excites, in health, to normal action only; alcohol tends to inflammation and disease. Food gives force to the body; alcohol excites reaction and wastes force, in the first place, and in the second, as a true narcotic, represses vital action and corresponding nutrition.—If alcohol does not act like food, neither does it behave like water. Water is the subtle but innocent vehicle of circulation, which dissolves the solid food, holds in play the chemical and vital reactions of the tissues, conveys the nutritive solutions from cell to cell, from tube to tube, and carries off and expels the effete matter. Water neither irritates tissue, wastes force, nor suppresses vital action: whereas alcohol does all three. Alcohol hardens solid tissue, thickens the blood, narcotizes the nerves, and in every conceivable direction antagonizes the operation and function of water—LEES.] The juices of the system will flow from every pore to dilute and weaken it, and to prevent its shriveling up the delicate membranes with which it comes in contact. The veins will take it up and bear it rapidly through the system. Every organ of elimination, all the scavengers of the body— the lungs, the kidneys, the perspiration glands, at once set to work to throw off the enemy. So surely is this the case, that the breath of a person who has drunk only a single glass of the lightest beer will betray the fact.
The alcohol thus eliminated is entirely unchanged. Nature apparently makes no effort to appropriate it. [Footnote: It was formerly a question considerably discussed, whether alcohol exists in the brain, or in the fluid found in the ventricles, in intoxicated persons. This was settled by Percy, who found alcohol in the brain and liver of dogs poisoned with alcohol, and of men who had died after excessive drinking. In these experiments, the presence of alcohol was determined by distillation, and the distilled substance burned with a blue flame, and dissolved camphor.— FLINT'S Physiology of Man.] It courses everywhere through the circulation, and into the great organs, with all its properties unmodified.
Alcohol, then, is not, like bread or beef, taken hold of, broken up by the mysterious process of digestion, and used by the body. [Footnote: Because of the difficulties of such an experiment, we have not yet been able to account satisfactorily by the excretions for all the alcohol taken into the stomach. This remains as yet one of the unsolved problems of physiological chemistry. To collect the whole of the insensible perspiration, for example, is well-nigh impossible. It was supposed at one time that a part of the alcohol is oxidized—i. e., burned, in the system. But such a process would impart heat, and it is now proved that alcohol cools, instead of warms, the blood. Moreover, the closest analysis fails to detect in the circulation any trace of the products of alcoholic combustion, such as aldehyde and acetic acid. "The fact," says Flint, "that alcohol is always eliminated, even when drunk in minute quantity, and that its elimination continues for a considerable time, gradually diminishing, renders it probable that all that is taken into the body is removed."] "It can not therefore be regarded as an aliment," or food.— FLINT. "Beer, wine, and spirits," says Liebig, "contain no element capable of entering into the composition of the blood or the muscular fiber." [Footnote: The small amount of nutritive substance, chiefly sugar derived from the grain or fruit used in the manufacture of beer or wine, can not, of course, be compared with that contained in bread or beef at the same cost. Liebig says, in his Letters on Chemistry, "We can prove, with mathematical certainty, that as much flour as can lie on the point of a table knife is more nutritious than eight quarts of the best Bavarian beer."] "That alcohol is incapable of forming any part of the body," remarks Cameron, "is admitted by all physiologists. It can not be converted into brain, nerve, muscle, or blood."
EFFECT UPON THE DIGESTION. [Footnote: The medical value of alcohol in its relations to digestion is not discussed in this book. The experiments of Dr. Henry Munroe, of Hull, published in the London Medical Journal, are here summarized as showing that the tendency to retard digestion is common to all forms of alcoholic drinks.
_______________________________________________________________________ Finely Minced | | | | Beef | 2d Hour | 4th Hour | 6th Hour | _______________________________________________________________________ I. | | Digesting | | Gastric Juice | Beef | and | Beef much | and water. | opaque. | separating. | loosened. | _______________________________________________________________________ | | Slightly | Slight | II. | No alteration | opaque, but | coating on | Gastric Juice | perceptible. | beef | beef. | with alcohol. | | unchanged. | | _______________________________________________________________________ III. | | Cloudy, | beef | Gastric Juice | No change. | with fur | partly | and pale ale. | | on beef. | loosened. | _______________________________________________________________________ ______________________________________________________ Finely Minced | | | Beef | 8th Hour | 10th Hour | ______________________________________________________ I. | | | Gastric Juice | Beef | Broken up | and water. | opaque. | into shreds. | ______________________________________________________ | | Solid on | II. | No visible | cooling | Gastric Juice | change. | Pepsin | with alcohol. | | precipitated. | ______________________________________________________ III. | | No digestion | Gastric Juice | No further | Pepsin | and pale ale. | change. | precipitated. | ______________________________________________________]
—Experiments tend to prove that alcohol coagulates and precipitates the pepsin from the gastric juice, and so puts a stop to its great work in the process of digestion.
The greed of alcohol for water causes it to imbibe moisture from the tissues and juices, and to inflame the delicate mucous membrane. It shows the power of Nature to adapt herself to circumstances, that the soft, velvety lining of the throat and stomach should come at length to endure the presence of a fiery liquid which, undiluted, would soon shrivel and destroy it. In self-defense, the juices pour in to weaken the alcohol, and it is soon hurried into the circulation. Before this can be done, "it must absorb about three times its bulk of water"; hence, very strong liquor may be retained in the stomach long enough to interfere seriously with the digestion, and to injure the lining coat. Habitual use of alcohol permanently dilates the blood vessels; thickens and hardens the membranes; in some cases, ulcerates the surface; and, finally, "so weakens the assimilation that the proper supply of food can not be appropriated." —FLINT. [Footnote: The case of St. Martin (p. 168) gave an excellent opportunity to watch the action of alcohol upon the stomach. Dr. Beaumont summarized his experiments thus: "The free, ordinary use of any intoxicating liquor, when continued for some days, invariably produced inflammation, ulcerous patches, and, finally, a discharge of morbid matter tinged with blood." Yet St. Martin never complained of pain in his stomach, the narcotic influence of the alcohol preventing the signal of danger that Nature ordinarily gives.]
EFFECT UPON THE LIVER.—Alcohol is carried by the portal vein directly to the liver. This organ, after the brain, holds the largest share. The influence of the poison is here easily traced. "The color of the bile is soon changed from yellow to green, and even to black;" the connective tissue between the lobules becomes inflamed; and, in the case of a confirmed drunkard, hardened and shrunk, the surface often assuming a nodulated appearance known as the "hobnailed liver." Morbid matter is sometimes deposited, causing what is called "Fatty degeneration," so that the liver is increased to twice or thrice its natural size.
EFFECT UPON THE KIDNEYS.—The kidneys, like the liver, are liable in time to undergo, through the influence of alcohol, a "Fatty degeneration," in which the cells become filled with particles of fat; [Footnote: Disabled by the fatty deposits, the kidneys are unable to separate the waste matter coming to them for elimination from the system. The poisonous material is poured back into the circulation, and often delirium ensues.—HUBBARD. Richardson states that his experience "is to the effect that seven out of every eight instances of kidney disease are attributable to alcohol."] the vessels lose their contractility; and, worst of all, the membranes may be so modified as to allow the albuminous part of the blood to filter through them, and so to rob the body of one of its most valuable constituents. [Footnote: This deterioration of structure frequently gives rise to what is known as "Bright's Disease."—RICHARDSON.]
DOES ALCOHOL IMPART HEAT?—During the first flush after drinking wine, for example, a sense of warmth is felt. This is due to the tides of warm blood that are being sent to the surface of the body, owing to the vascular enlargement and to the rapid pumping of the heart. There is, however, no fresh heat developed. On the contrary, the bringing the blood to the surface causes it to cool faster, reaction sets in, a chilliness is experienced as one becomes sober, and a delicate thermometer placed under the tongue of the inebriate may show a fall of even two degrees below the standard temperature of the body. Several hours are required to restore the usual heat.
As early as 1850, Dr. N. S. Davis, of Chicago, ex-President of the American Medical Association, instituted an extensive series of experiments to determine the effect of the different articles of food and drinks on the temperature of the system. He conclusively proved that, during the digestion of all kinds of food, the temperature of the body is increased, but when alcohol is taken, either in the form of fermented or distilled beverages, the temperature begins to fall within a half hour, and continues to decrease for two or three hours, and that the reduction of temperature, in extent as well as in duration, is in exact proportion to the amount of alcohol taken.
It naturally follows that, contrary to the accepted opinion, liquor does not fortify against cold. The experience of travelers at the North coincides with that of Dr. Hayes, the Arctic explorer, who says: "While fat is absolutely essential to the inhabitants and travelers in arctic countries, alcohol is, in almost any shape, not only completely useless, but positively injurious. I have known strong, able-bodied men to become utterly incapable of resisting cold in consequence of the long-continued use of alcoholic drink."
DOES ALCOHOL IMPART STRENGTH?—Experience shows that alcohol weakens the power of undergoing severe bodily exertion. [Footnote: Dr. McRae, in speaking of Arctic exploration, at the meeting of the American Association for the Advancement of Science, held at Montreal in 1856, said: "The moment that a man had swallowed a drink of spirits, it was certain that his day's work was nearly at an end. It was absolutely necessary that the rule of total abstinence be rigidly enforced, if we would accomplish our day's task. The use of liquor as a beverage when we had work on hand, in that terrific cold, was out of the question."] Men who are in training for running, rowing, and other contests where great strength is required, deny themselves all liquors, even when they are ordinarily accustomed to their use.
Dr. Richardson made some interesting experiments to show the influence of alcohol upon muscular contraction. He carefully weighted the hind leg of a frog, and, by means of electricity, stimulating the muscle to its utmost power of contraction, he found out how much the frog could lift. Then administering alcohol, he discovered that the response of the muscle to the electrical current became feebler and feebler, as the narcotic began to take effect, until, at last, the animal could raise less than half the amount it lifted by the natural contraction when uninfluenced by alcohol.
EFFECT UPON THE WASTE OF THE BODY.—The tendency of alcohol is to cause a formation of an unstable substance resembling fat, [Footnote: The molecular deposits equalizing the waste of the system do not go on regularly under the influence of alcohol; the tissues are not kept up to their standard; and, in time, their composition is changed by a deposit of an amorphous matter resembling fat. This is an unstable substance, and the functions of animal life all retrograde.—HUBBARD, The Opium Habit and Alcoholism.] and so the use of liquor for even a short time will increase the weight. But a more marked influence is to check the ordinary waste of the system, so that "the amount of carbonic acid exhaled from the lungs may be reduced as much as thirty to fifty per cent."—HINTON. The life process is one of incessant change. Its rapidity is essential to vigor and strength. When the functions are in full play, each organ is being constantly torn down, and as constantly rebuilt with the materials furnished from our food. Anything that checks this oxidation of the tissues, or hinders the deposition of new matter, disturbs the vital functions. Both these results are the inevitable effects of alcohol; for, since the blood contains less oxygen and more carbonic acid, and the power of assimilating the food is decreased, it follows that every process of waste and repair must be correspondingly weakened. The person using liquor consequently needs less bread and beef, and so alcohol seems to him a food—a radical error, as we have shown.
ALCOHOL CREATES A PROGRESSIVE APPETITE FOR ITSELF.—When liquor is taken, even in the most moderate quantity, it soon becomes necessary, and then arises a craving demand for an increased amount to produce the original effect. No food creates this constantly augmenting want. A cup of milk drank at dinner does not lead one to go on, day by day, drinking more and more milk, until to get milk becomes the one great longing of the whole being. Yet this is the almost universal effect of alcohol. Hunger is satisfied by any nutritious food: the dram-drinker's thirst demands alcohol. The common experience of mankind teaches us the imminent peril that attends the formation of this progressive poison habit. A single glass taken as a tonic may lead to the drunkard's grave.
Worse than this, the alcoholic craving may be transmitted from father to son, and young persons often find themselves cursed with a terrible disease known as alcoholism—a keen, morbid appetite for liquor that demands gratification at any cost—stamped upon their very being through the reckless indulgence of this habit on the part of some one of their ancestors. [Footnote: The American Medical Association, at their meeting in St. Paul, Minnesota (1883), restated in a series of resolutions their conviction, that "alcohol should be classed with other powerful drugs; that when prescribed medically, it should be done with conscientious caution and a sense of great responsibility; that used as a beverage it is productive of a large amount of physical and mental disease; that it entails diseased and enfeebled constitutions upon offspring, and that it is the cause of a large percentage of the crime and pauperism of our large cities and country."]
THE LAW OF HEREDITY is, in this connection, well worth consideration. "The world is beginning to perceive," says Francis Galton, "that the life of each individual is, in some real sense, a continuation of the lives of his ancestors." "Each of us is the footing up of a double column of figures that goes back to the first pair." "We are omnibuses," remarks Holmes, "in which all our ancestors ride." We inherit from our parents our features, our physical vigor, our mental faculties, and even much of our moral character. Often, when one generation is skipped, the qualities will reappear in the following one. The virtues, as well as the vices, of our forefathers, have added to, or subtracted from, the strength of our brain and muscle. The evil tendencies of our natures, which it is the struggle of our lives to resist, constitute a part of our heirlooms from the past. Our descendants, in turn, will have reason to bless us only if we hand down to them a pure healthy physical, mental, and moral being.
"There is a marked tendency in nature to transmit all diseased conditions. Thus, the children of consumptive parents are apt to be consumptives. But of all agents, alcohol is the most potent in establishing a heredity that exhibits itself in the destruction of mind and body. [Footnote: Nearly all the diseases springing from indulgence in distilled and fermented liquors are liable to become hereditary, and to descend to at least three or four generations, unless starved out by uncompromising abstinence. But the distressing aspect of the heredity of alcohol is the transmitted drink- crave. This is no dream of an enthusiast, but the result of a natural law. Men and women upon whom this dread inheritance has been forced are everywhere around us, bravely struggling to lead a sober life.—DR. NORMAN KERR.] Its malign influence was observed by the ancients long before the production of whiskey or brandy, or other distilled liquors, and when fermented liquors or wines only were known. Aristotle says, 'Drunken women have children like unto themselves,' and Plutarch remarks, 'One drunkard is the father of another.' The drunkard by inheritance is a more helpless slave than his progenitor, and his children are more helpless still, unless on the mother's side there is an untainted blood. For there is not only a propensity transmitted, but an actual disease of the nervous system."—DR. WILLARD PARKER. [Footnote: The subject of alcohol is continued in the chapter on the Nervous System.]
PRACTICAL QUESTIONS.
1. How do clothing and shelter economize food?
2. Is it well to take a long walk before breakfast?
3. Why is warm food easier to digest than cold?
4. Why is salt beef less nutritious than fresh? [Footnote: The French Academicians found that flesh soaked in water so as to deprive it of its mineral matter and juices, lost its nutritive value, and that animals fed on it soon died. Indeed, for all purposes of nutrition, Liebig said it was no better than stones, and the utmost torments of hunger were hardly sufficient to induce them to continue the diet. There was plenty of nutritive food, but there was no medium for its solution and absorption, and hence it was useless.] 5. What should be the food of a man recovering from a fever?
6. Is a cup of black coffee a healthful close to a hearty dinner?
7. Should iced water be used at a meal?
8. Why is strong tea or coffee injurious?
9. Should food or drink be taken hot?
10. Are fruitcakes, rich pastry, and puddings wholesome?
11. Why are warm biscuit and bread hard of digestion?
12. Should any stimulants be used in youth?
13. Why should bread be made spongy?
14. Which should remain longer in the mouth, bread or meat?
15. Why should cold water be used in making soup, and hot water in boiling meat?
16. Name the injurious effects of overeating.
17. Why do not buckwheat cakes, with syrup and butter, taste as well in July as in January?
18. Why is a late supper injurious?
19. What makes a man "bilious"?
20. What is the best remedy? Ans. Diet to give the organs rest, and active exercise to arouse the secretions and the circulation.
21. What is the practical use of hunger?
22. How can jugglers drink when standing on their heads?
23. Why do we relish butter on bread?
24. What would you do if you had taken arsenic by mistake? (See Appendix.)
25. Why should ham and sausage be thoroughly cooked?
26. Why do we wish butter on fish, eggs with tapioca, oil on salad, and milk with rice?
27. Explain the relation of food to exercise.
28. How do you explain the difference in the manner of eating between carnivorous and herbivorous animals?
29. Why is a child's face plump and an old man's wrinkled?
30. Show how life depends on repair and waste.
31. What is the difference between the decay of the teeth and the constant decay of the body?
32. Should biscuit and cake containing yellow spots of soda be eaten?
33. Tell how the body is composed of organs, how organs are made up of tissues, and how tissues consist of cells.
34. Why do we not need to drink three pints of water per day?
35. Why, during a pestilence, are those who use liquors as a beverage the first, and often the only victims?
36. What two secretions seem to have the same general use?
37. How may the digestive organs be strengthened?
38. Is the old rule, "after dinner sit awhile," a good one?
39. What would you do if you had taken laudanum by mistake? Paris Green? Sugar of lead? Oxalic acid? Phosphorus from matches? Ammonia? Corrosive sublimate? (See p. 265.)
40. What is the simplest way to produce vomiting, so essential in case of accidental poisoning?
41. In what way does alcohol interfere with the digestion?
42. Is alcohol assimilated?
43. What is the effect of alcohol on the albuminous substances?
44. Is there any nourishment in beer?
45. Show how the excessive use of alcohol may first increase, and, afterward, decrease, the size of the liver.
46. Will liquor help one to endure cold and exposure?
47. What is a fatty degeneration of the kidneys?
48. Contrast the action of alcohol and water in the body.
49. Is alcohol, in any proper sense of the term, a food?
50. Does liquor strengthen the muscles of a working man?
51. Is liquor a wholesome "tonic"?
52. Is it a good plan to take a glass of liquor before dinner?
VII.
THE NERVOUS SYSTEM.
"Mark then the cloven sphere that holds
All thoughts in its mysterious folds,
That feels sensation's faintest thrill,
And flashes forth the sovereign will;
Think on the stormy world that dwells
Lock'd in its dim and clustering cells;
The lightning gleams of power it sheds
Along its hollow, glassy threads!"
"As a king sits high above his subjects upon his throne, and from it speaks behests that all obey, so from the throne of the brain cells is all the kingdom of a man directed, controlled, and influenced. For this occupant, the eyes watch, the ears hear, the tongue tastes, the nostrils smell, the skin feels. For it, language is exhausted of its treasures, and life of its experience; locomotion is accomplished, and quiet insured. When it wills, body and spirit are goaded like overdriven horses. When it allows, rest and sleep may come for recuperation. In short, the slightest penetration may not fail to perceive that all other parts obey this part, and are but ministers to its necessities."—Odd Hours of a Physician. ANALYSIS OF THE NERVOUS SYSTEM.
| 1. THE STRUCTURE | | _ | 1. Description. | | 1. The Brain……..| 2. The Cerebrum. | | |_3. The Cerebellum. | | _ | | 2. The Spinal Cord..| 1. Its Composition. | | |_2. Medulla Oblongata. | | _ | 2. ORGANS OF | | 1. Description. | THE NERV- | | 2. Motory and Sensory. | OUS SYSTEM..| | 3. Transfer of Pain. | | | 4. The Spinal Nerves— | | | 31 Pairs. | |_3. The Nerves…….| 5. The Cranial Nerves— | | 12 Pairs. | | 6. Sympathetic System. | | 7. Crossing of Cords. | | 8. Reflex Action. | | 9. Uses of Reflex | | Action_ | _ | | 1. Brain Exercise. | | 2. Connection between Brain Growth and Body Growth. | 3. HYGIENE…..| 3. Sleep. | | 4. Effect of Sleeping Draughts. | |5. Sunlight. | | 4. WONDERS OF THE BRAIN. | | | 1. Alcohol (Con'd.) | | _ | 1. Stage of Excitement. | || | 2. Stage of Muscular | || | Weakness. | || 1. Effect of Alco- | 3. Stage of Mental | || hol upon the | Weakness. | || Nervous System | 4. Stage of Unconscious- | || | ness._ | || | || 2. Effect upon the Brain | ||3. Effect upon the Mental and Moral Powers. | | | | 2. Tobacco. | | | || 1. Constituents of Tobacco. | 5. ALCOHOLIC || 2. Physiological Effects. | DRINKS AND|| 3. Possible Disturbances produced by Smoking. |_ NARCOTICS.|| 4. Influence upon the Nervous System. || 5. Is Tobacco a Food? ||6. Influence of Tobacco on Youth. | | | 1. Description. | 3. Opium…………| 2. Physiological | | Effects._ | 4. Chloral Hydrate. | 5. Chloroform. |_6. Cocaine.
THE NERVOUS SYSTEM. [Footnote: The organs of circulation, respiration, and digestion, of which we have already spoken, are often called the vegetative functions, because they belong also to the vegetable kingdom. Plants have a circulation of sap through their cells corresponding to that of the blood through the capillaries. They breathe the air through their leaves, which act the part of lungs, and they take in food which they change into their own structure by a process which answers to that of digestion. The plant, however, is a mere collection of parts incapable of any combined action. On the other hand, the animal has a nervous system which binds all the organs together.]
STRUCTURE.—The nervous system includes the brain, the spinal cord, and the nerves. It is composed of two kinds of matter— the white, and the gray. The former consists of minute, milk-white, glistening fibers, sometimes as small as 1/25000 of an inch in diameter; the latter is made up of small, ashen-colored cells, forming a pulp-like substance of the consistency of blancmange. [Footnote: In addition to the cells, the gray substance contains also nerve fibers continuous with the white fibers, but generally much smaller. These form half the bulk of the gray substance of the spinal cord, and a large part of the deeper layer of the gray matter in the brain.—LEIDY'S Anatomy, p. 507.] This is often gathered in little masses, termed ganglions (ganglion, a knot), because, when a nerve passes through a group of the cells, they give it the appearance of a knot. The nerve fibers are conductors, while the gray cells are generators, of nervous force. [Footnote: What this force is we do not know. In some respects it is like electricity, but, in others, it differs materially. Its velocity is about thirty three meters per second.—Popular Physics, p. 244, Note.] The ganglia, or nervous centers, answer to the stations along a telegraphic line, where messages are received and transmitted, and the fibers correspond to the wires that communicate between different parts.
FIG. 50.
[Illustration: The Nervous System. A, cerebrum; B, cerebellum.]
The BRAIN is the seat of the mind. [Footnote: In proportion to the rest of the nervous matter in the body, it is larger in man than in any of the lower animals. It is the function which the brain performs that distinguishes man from all other animals, and it is by the action of his brain that he becomes a conscious, intelligent, and responsible being. The brain is the seat of that knowledge which we express when we say I. I know it, I feel it, I saw it, are expressions of our individual consciousness, the seat of which is the brain. It is when the brain is at rest in sleep that there is least consciousness. The brain may be put under the influence of poisons, such as alcohol and chloroform, and then the body is without consciousness. From these and other facts the brain is regarded as the seat of consciousness.—LANKESTER.] Its average weight is about fifty ounces. [Footnote: Cuvier's brain weighed 64 1/2 ounces; Webster's, 53 1/2 ounces; James Fisk's, 58 ounces; Ruloff's, 59 ounces; an idiot's, 19 ounces. See Table in FLINT'S Nervous System.] It is egg-shaped, and, soft and yielding, fills closely the cavity of the skull. It reposes securely on a water bed, being surrounded by a double membrane (arachnoid), delicate as a spider's web, which forms a closed sac filled, like the spaces in the brain itself, with a liquid resembling water. Within this, and closely investing the brain, is a fine tissue (pia mater), with a mesh of blood vessels which dips down into the hollows, and bathes them so copiously that it uses one fifth of the entire circulation of the body. Around the whole is wrapped a tough membrane (dura mater), which lines the bony box of the skull, and separates the various parts of the organ by strong partitions. The brain consists of two parts—the cerebrum, and the cerebellum.
The CEREBRUM fills the front and upper part of the skull, and comprises about seven eighths of the entire weight of the brain. As animals rise in the scale of life, this higher part makes its appearance. It is a mass of white fibers, with cells of gray matter sprinkled on the outside, or lodged here and there in ganglia. It is so curiously wrinkled and folded as strikingly to resemble the meat of an English walnut. This structure gives a large surface for the gray matter,—sometimes as much as six hundred and seventy square inches. The convolutions are not noticeable in an infant, but increase with the growth of the mind, their depth and intricacy being characteristic of high mental power.
FIG. 51.
[Illustration: Surface of the Cerebrum.]
The cerebrum is divided into two hemispheres, connected beneath by fibers of white matter. Thus we have two brains, [Footnote: This doubleness has given rise to some curious speculations. In the case of the hand, eye, etc, we know that the sensation is made more sure. Thus we can see with one eye, but not so well as with both. It is perhaps the same with the brain. We may sometimes carry on a train of thought, "build an air castle" with one half of our brain, while the other half looks on and watches the operation; or, we may read and at the same time think of something else. So in delirium, a patient often imagines himself two persons, thus showing a want of harmony between the two halves.—DRAPER, Human Physiology, p. 320.] as well as two hands and two eyes. This provides us with a surplus of brains, as it were, which can be drawn upon in an emergency. A large part of one hemisphere has been destroyed without particularly injuring the mental powers, [Footnote: A pointed iron bar, three and a half feet long and one inch and a quarter in diameter, was driven by the premature blasting of a rock completely through the side of the head of a man who was present. It entered below the temple, and made its exit at the top of the forehead, just about the middle line. The man was at first stunned, and lay in a delirious, semistupefied state for about three weeks. At the end of sixteen months, however, he was in perfect health, with wounds healed and mental and bodily functions unimpaired, except that sight was lost in the eye of the injured side.— DALTON. It is noticeable, however, that the man became changed in disposition, fickle, impatient of restraint, and profane, which he was not before. He died epileptic, nearly thirteen years after the injury. The tamping iron and the skull are preserved in the Warren Anatomical Museum, Boston.]—just as a person has been blind in one eye for a long time without having discovered his loss. The cerebrum is the center of intelligence and thought. [Footnote: In man, the cerebrum presents an immense preponderance in weight over other portions of the brain; in some of the lower animals, the cerebrum is even less in weight than the cerebellum. Another interesting point is the development of cerebral convolutions in certain animals, by which the relative amount of gray matter is increased. In fishes, reptiles, and birds, the surface of the hemispheres is smooth; but, in many mammalia, especially in those remarkable for intelligence, the cerebrum presents a greater or less number of convolutions, as it does in the human subject.—FLINT. The average weight of the human brain in proportion to the entire body is about 1 to 36. The average of mammalia is 1 to 186; of birds, 1 to 212; of reptiles, 1 to 1,321; and of fishes, 1 to 5,668. There are some animals in which the weight of the brain bears a higher proportion to the body than it does in man; thus in the blue-headed tit, the proportion is as 1 to 12; in the goldfinch, as 1 to 24; and in the field mouse, as 1 to 31. "It does not hence follow, however, that the cerebrum is larger in proportion; in fact, it is probably not nearly so large; for in birds and rodent animals the sensory ganglia form a very considerable portion of the entire brain. M. Baillarger has shown that the surface and the bulk of the cerebral hemispheres are so far from bearing any constant proportion to each other in different animals that, notwithstanding the depth of the convolutions in the human cerebrum, its bulk is two and a half times as great in proportion to its surface as it is in the rabbit, the surface of whose cerebrum is smooth. The size of the cerebrum, considered alone, is not, however, a fair test of its intellectual power. This depends upon the quantity of vesicular matter which it contains, as evinced not only by superficial area, but by the number and depth of the convolutions and by the thickness of the cortical layer."—CARPENTER.] Persons in whom it is seriously injured or diseased often become unable to converse intelligently, both from inability to remember words and from loss of power to articulate them.
THE CEREBELLUM lies below the cerebrum, and in the back part of the head (Fig. 50). It is about the size of a small fist. Its structure is similar to that of the brain proper, but instead of convolutions it has parallel ridges, which, letting the gray matter down deeply into the white matter within, give it a peculiar appearance, called the arbor vitæ, or tree of life (Fig. 55). This part of the brain is the center for the control of the voluntary muscles, [Footnote: The exact nature of the functions of the cerebellum is one of those problems concerning which there is no unanimity of opinion amongst physiologists. It may be premised, however, that the knowledge we at present possess does enable us to come to one very important conclusion with respect to the functions of the cerebellum,—it enables us to say that this organ has no independent function either in the province of mind or in the province of motility. And we may perhaps safely affirm still further, that the cerebellum is much more intimately concerned with the production of bodily movements than with the evolution of mental phenomena. The anatomical distinctness of the cerebellum from the larger brain and other parts of the nervous system is more apparent than real….That there is an habitual community of action between the cerebellum and the spinal cord is, I believe, doubted by none, and the fact that an intimate functional relationship exists between the cerebrum and the cerebellum is shown by the circumstance that atrophy of one cerebral hemisphere entails a corresponding atrophy of the opposite half of the cerebellum. The subordinate or supplementary nature of the cerebellar function, however, in this latter relation seems equally well shown by the fact that atrophy of one side of the cerebellum (when it occurs as the primary event) does not entail any appreciable wasting in the opposite half of the cerebrum. What other conclusion can be drawn? If the cutting off of certain cerebral stimuli leads to a wasting of the opposite half of the cerebellum, this would seem to show that each half of the cerebellum is naturally called into activity in response to, or conjointly with, the opposite cerebral hemisphere. Whilst conversely, if atrophy of one half of the cerebellum does not entail a relative diminution in the opposite cerebral hemisphere, this would go to show that the cerebral hemispheres do not act in response to cerebellar stimuli, since their nutrition does not suffer when such stimuli are certainly absent. The action of the cerebrum is therefore shown to be primary, whilst that of the cerebellum is secondary or subordinate in the performance of those functions in which they are both concerned.—H. CHARLTON BASTIAN, Paralysis from Brain Disease.] particularly those of locomotion. Persons in whom it is injured or diseased walk with tottering and uncertain movements as if intoxicated, and can not perform any orderly work.
THE SPINAL CORD occupies the cavity of the backbone. It is protected by the same membranes as the brain, but, unlike it, the white matter is on the outside, and the gray matter is within. Deep fissures separate it into halves (Fig. 50), which are, however, joined by a bridge of the same substance. Just as it starts from the brain, there is an expansion called the medulla oblongata (Fig. 55).
THE NERVES are glistening, silvery threads, composed, like the spinal cord, of white matter without and gray within. They ramify to all parts of the body. Often they are very near each other, yet are perfectly distinct, each conveying its own impression. [Footnote: Press two fingers together, and, closing the eyes, let some one pass the point of a pin lightly from one to the other; you will be able to tell which is touched, yet if the nerves came in contact with each other anywhere in their long route to the brain, you could not thus distinguish.] Those which carry the orders of the mind to the different organs are called the motory nerves; while those which bring back impressions which they receive are styled sensory nerves. If the sensory nerve leading to any part be cut, all sensation in that spot will be lost, while motion will remain; if the motory nerve be cut, all motion will be destroyed, while sensation will exist as before.
TRANSFER OF PAIN.—Strictly speaking, pain is not in any organ, but in the mind, since only that can feel. When any nerve brings news to the brain of an injury, the mind refers the pain to the end of the nerve. A familiar illustration is seen in the "funny bone" behind the elbow. Here the nerve (ulnar) gives sensation to the third and fourth fingers, in which, if this bone be struck, the pain will seem to be. Long after a limb has been amputated, pain will be felt in it, as if it still formed a part of the body—any injury in the stump being referred to the point to which the nerve formerly led. [Footnote: Only about five per cent. of those who suffer amputation lose the feeling of the part taken away. There is something tragical, almost ghastly, in the idea of a spirit limb haunting a man through his life, and betraying him in unguarded moments into some effort, the failure of which suddenly reminds him of his loss. A gallant fellow, who had left an arm at Shiloh, once, when riding, attempted to use his lost hand to grasp the reins while with the other he struck his horse. A terrible fall was the result of his mistake. When the current of a battery is applied to the nerves of an arm stump, the irritation is carried to the brain, and referred to all the regions of the lost limb. On one occasion a man's shoulder was thus electrized three inches above the point where the limb was cut off. For two years he had ceased to be conscious of his limb. As the electric current passed through, the man, who had been profoundly ignorant of its possible effects, started up, crying, "Oh, the hand! the hand!" and tried to seize it with the living grasp of the sound fingers. No resurrection of the dead could have been more startling.—DR. MITCHELL on "Phantom Limbs" in Lippincott's Magazine.]
The nerves are divided into three general classes—the spinal, the cranial, and the sympathetic.
FIG. 54.
[Illustration: P, posterior root of a spinal nerve; G, ganglion; A, anterior root; S, spinal nerve. The white portions of the figure represent the white fibers; and the dark, the gray.]
THE SPINAL NERVES, of which there are thirty-one pairs, issue from the spinal cord through apertures provided for them in the backbone. Each nerve arises by two roots; the anterior is the motory, and the posterior the sensory one. The posterior alone connects directly with the gray matter of the cord, and has a small ganglion of gray matter of its own at a little distance from its origin. These roots soon unite, i. e., are bound up in one sheath, though they preserve their special functions. When the posterior root of a nerve is cut, the animal loses the power of feeling, and when the anterior root is cut, that of motion.
THE CRANIAL NERVES, twelve pairs in number, spring from the lower part of the brain and the medulla oblongata.
1. The olfactory, or first pair of nerves, ramify through the nostrils, and are the nerves of smell.
2. The optic, or second pair of nerves, pass to the eyeballs, and are the nerves of vision.
3, 4, 6. The motores oculi (eye movers) are three pairs of nerves used to move the eyes.
5. The trifacial, or fifth pair of nerves, divide each into three branches—hence the name—the first to the upper part of the face, eyes, and nose; the second to the upper jaw and teeth; the third to the lower jaw and the mouth, where it forms the nerve of taste. These nerves are implicated when we have the toothache or neuralgia.
7. The facial, or seventh pair of nerves, are distributed over the face, and give it expression. [Footnote: If it is palsied, on one side there will be a blank, while the other side will laugh or cry, and the whole face will look funny indeed. There were some cruel people in the middle ages who used to cut the nerve and deform children's faces in this way, for the purpose of making money of them at shows. When this nerve was wrongly supposed to be the seat of neuralgia, or tic douloureux, it was often cut by surgeons. The patient suffered many dangers, and no relief of pain was gained.—MAPOTHER.]
FIG. 55.
[Illustration: The Brain and the origin of the twelve pairs of Cranial Nerves. F, E, the cerebrum; D, the cerebellum, showing the arbor vitæ; G, the eye; H, the medulla oblongata; A, the spinal cord; C and B, the first two pairs of spinal nerves.]
8. The auditory, or eighth pair of nerves, go to the ears, and are the nerves of hearing.
9. The glos-so-pha-ryn'-ge-al, or ninth pair of nerves, are distributed over the mucous membrane of the pharynx, tonsils, etc.
10. The pneu-mo-gas'-tric, or tenth pair of nerves, preside over the larynx, lungs, liver, stomach, and one branch extends to the heart. This is the only nerve which goes so far from the head.
11. The accessory, or eleventh pair of nerves, rise from the spinal cord, run up to the medulla oblongata, and thence leave the skull at the same opening with the ninth and tenth pairs. They regulate the vocal movements of the larynx.
12. The hyp-o-glos'-sal, or twelfth pair of nerves, give motion to the tongue.
FIG. 56.
[Illustration: Spinal Nerve, Sympathetic Cord, and the Network of Sympathetic Nerves around the Internal Organs. K, aorta; A, ophagus; B, diaphragm; C, stomach.]
THE SYMPATHETIC SYSTEM contains the nerves of organic life. It consists of a double chain of ganglia on either side of the backbone, extending into the chest and abdomen. From, these, delicate nerves, generally soft and of a grayish color, run to the organs on which life depends—the heart, lungs, stomach, etc.—to the blood vessels, and to the spinal and cranial nerves over the body. Thus the entire system is bound together with cords of sympathy, so that, "if one member suffers, all the members suffer with it."
Here lies the secret of the control exercised by the brain over all the vital operations. Every organ responds to its changing moods, especially those of respiration, circulation, digestion, and secretion,—processes intimately linked with this system, and controlled by it. (See p. 330.)
CROSSING OF CORDS.—Each half of the body is presided over, not by its own half of the brain, but that of the opposite side. The motory nerves, as they descend from the brain, in the medulla oblongata, cross each other to the opposite side of the spinal cord. So the motor nerves of the right side of the body are connected with the left side of the brain, and vice versa. Thus a derangement in one half of the brain may paralyze the opposite half of the body. The nerves going to the face do not thus cross, and therefore the face may be motionless on one side, and the limbs on the other. Each of the sensory fibers of the spinal nerves crosses over to the opposite side of the spinal cord, and so ascends to the brain; an injury to the spinal cord may, therefore, cause a loss of motion in one leg and of feeling in the other.
REFLEX ACTION.—Since the gray matter generates the nervous force, a ganglion is capable of receiving an impression, and of sending back or reflecting it so as to excite the muscles to action. This is done without the consciousness of the mind. [Footnote: Instances of an unconscious working of the mind are abundant. An illustration, often quoted, is given, as follows, by Dr. Abercrombie, in his Intellectual Powers:
"A lawyer had been excessively perplexed about a very complicated question. An opinion was required from him, but the question was one of such difficulty that he felt very uncertain how he should render it. The decision had to be given at a certain time, and he awoke in the morning of that day with a feeling of great distress. He said to his wife, 'I had a dream, and the whole thing was clearly arranged before my mind, and I would give anything to recover the train of thought.' His wife said to him, 'Go and look on your table.' She had seen him get up in the night and go to his table and sit down and write. He did so, and found there the opinion which he had been most earnestly endeavoring to recover, lying in his own handwriting. There was no doubt about it whatever."