While, therefore, it must be classed technically as a food, it is in many respects an unsuitable food, and its place can be taken with great advantage by other substances."-KENDRICK, Physiology (Glasgow, 1889), Vol. II, page 19.

"Alcohol is thus, within narrow limits, a food. . . It is, moreover, a very uneconomical food. Much more nutriment would have been obtained from the barley or curds from which it was made. The value of alcohol within narrow limits is not as a food, but as a stimulant, not only to digestion, but to the heart and brain."— HALLIBURTON, Text-book of Chemical and Pathological Physiology, 1891, page 600.

"According to Dupré, one grain of alcohol oxidized in the body evolves 7134 units of heat, while the same amount of lean beef gives off only 1482 units of heat. It has been estimated that 9.5 ounces of lean beef (equal to about 2 ounces of alcohol) will supply the force necessary to maintain the circulation and respiration for one day. That is, four ounces of strong spirit will suffice for this purpose. These considerations warrant the statement that, in a certain sense, alcohol is a food, i.e. that it is capable of being used for the purpose of the organism."—H. C. WOOD, Therapeutics.

"Alcohol in small doses is of great use in conditions of temporary want or where food is taken in insufficient quantity. When alcohol is taken regularly, more especially in large doses, it affects the nervous system and undermines the physical and corporal faculties, partly by the action of the impurities which it may contain, such as fusel oil, which has a poisonous effect on the nervous system; partly by its direct effects, such as catarrh and inflammation of the digestive organs, which it produces; and lastly by its effects on the normal metabolism.”. - LANDOIS & STERLING, Textbook on Human Physiology (London, 1891), page 437.

On the other hand, we know that although alcohol may technically be considered as a food, it is a very unsatisfactory food. In large doses, it is, undoubtedly, poisonous. A commonly accepted definition of a poison is that it is any substance which, when taken into the body, tends to cause serious detriment to health or the death of the organism.

That alcohol may do this is well known by scientists. The following quotations show that a large number of very eminent professors and physicians have this belief.

"From an exhaustive definition we shall have to class every substance as a poison which, on becoming mixed with the blood, causes a disturbance in the function of any organ. That alcohol is such a poison cannot be doubted. . . . Very appropriately has the English language named the

disturbance caused by alcoholic beverages intoxication, which, by derivation, means poisoning.” — DR. Adolph Fick, Professor of Physiology, Würzburg, Germany.

"Ethyl alcohol, even when diluted as in wine, beer, and cider, is a poison which changes pathologically the tissues of the body and leads to fatty degeneration. Of course I am not speaking here of the smallest doses. However, the latter (for example, half a liter of beer or a glass of wine) are also poisonous, because they injure the brain by producing paralysis and derangement of function; that is clearly demonstrated by the experiments of Kraepelin, Smith, Fürer, Aschaffenburg, etc. The same have never been controverted. The most moderate drinking of alcohol is quite useless for the individual, but by means of example and fashion produces an incalculable social injury and misery to the masses, since all cannot remain moderate, and the entirely moderate remains at last the exception." DR. AUGUST FOREL, Professor of Psychiatry in the University of Zurich. "All the alcohols are poisons." DUJARDIN-BEAUMETZ and AUDIGE.

"Is alcohol a poison? I reply, Yes. It answers to the description of a poison. It possesses an inherent deleterious property which, when introduced into the system, is capable of destroying life, and it has its place with arsenic, belladonna, prussic acid, opium, etc."- - DR. WILLARD PARKER, late Professor of Surgery in the College of Physicians and Surgeons, New York; Consulting Physician to Bellevue, Mount Sinai, Roosevelt, and the New York hospitals.

"It [alcohol] leads to degeneration of the tissues; it damages the health; it injures the intellect. Short of drunkenness, that is, in those effects of it which stop short of drunkenness, I should say from my experience that alcohol is the most destructive agent we are aware of in this country.". SIR WILLIAM GULL, M.D., F.R.S., Consulting Physician to Guy's Hospital, London.

Alcohol is,

"We know that alcohol is mostly oxidized in our body. therefore, without doubt, a source of living energy in our body, but it does not follow from this that it is also a nutriment. To justify this assumption, proof must be furnished that the living energy set free by its oxidation is utilized for the purpose of a normal function. It is not enough that potential energy is transformed into living energy; the transformation must take place at the right time and place, and at definite points in definite elements of the tissues. These elements are not adapted to be fed with every sort of oxidizable material. We do not know whether alcohol can furnish to the muscles and nerves a source of energy for the performance of their functions. . . . In general, alcohol has only paralyzing properties, etc."— G. BUNGE, Lehrbuch der Physiologischen und Pathologischen Chemie (Leipsic, 1894), page 124.

"Alcohol, also, when not taken in too large quantities, may be oxidized in the body, and furnish a not inconsiderable amount of energy. It is,

however, a matter of controversy at present, whether alcohol in small doses can be considered a true foodstuff capable of serving as a direct source of energy, and of replacing a corresponding amount of fats and carbohydrates in the daily diet.' - WILLIAM H. HOWELL, American Textbook of Physiology (Philadelphia, 1896), page 297.

"The nutritive value of alcohol has been the subject of considerable discussion and not a few experiments. Some of these tend to show that in moderate non-poisonous doses it acts as a non-proteid food in diminishing the oxidation of proteid, doubtless by becoming itself oxidized. Its action, however, in this respect, is relatively small, and, indeed, a certain proportion of the alcohol ingested is exhaled with the air of respiration.

"Moreover, in large doses it [alcohol] may act in a contrary manner, increasing the waste of tissue proteid. It cannot, in fact, be doubted that any small production of energy resulting from its oxidation is more than counterbalanced by its deleterious influence as a drug upon the tissue elements, and especially upon those of the nervous system."-E. A. SCHAEFER, A Text-book of Physiology (1898), page 882.

The Use of Tobacco. A well-known authority defines a narcotic as a substance "which directly induces sleep, blunts the senses, and, in large amounts, produces complete insensibility" Tobacco, opium, chloral, and cocaine are examples of narcotics. Tobacco owes its narcotic influence to a strong poison known as nicotine. In experiments with jellyfish and other lowly organized animals, the author has found as small a per cent as one part of nicotine to one hundred thousand parts of sea water to be sufficient to profoundly affect an animal placed within it. Nicotine in a pure form is so powerful a poison that two or three drops would be sufficient to cause the death of a man by its action upon the nervous system, especially the nerves controlling the beating of the heart. This action is well known among boys training for athletic contest. The heart is affected, boys become "short winded" as a result of the action on the heart. It has been demonstrated that tobacco has, too, an important effect on muscular development. The stunted appearance of the young smoker is well known.

XXVIII. DIGESTION AND ABSORPTION

Purpose of Digestion. We have learned that starch and proteid food of plants are formed in the leaves. A plant, however, is unable to make use of the food in this condition. Before it can

Picture of the organs of digestion; a, intestine, leading out of the pylorus; b, liver; c, esophagus; d, pancreas; e, stomach; f, spleen; g, i, j, k, m, n, parts of large intestine; h, l, small intestine. From Johonnot and Bouton.

be used it is changed into a soluble form, such as grape sugar. In this state it can be passed from cell to cell by the process of osmosis, and can be used to build new cells or to release energy. The same condition exists in animals. In order that food may be of use to man, it must be changed into a state that will allow of its passage in a soluble form through the walls of the alimentary canal or food tube. Digestion consists in the changing of foods from an insoluble to a soluble form, so that they may pass through the walls of the alimentary canal and become part of the blood.

—

Alimentary Canal. In all vertebrate animals, including man, food is normally taken in the mouth and passed through a food tube during the process of digestion. This tube is composed of different portions, named, respectively, as we pass from the mouth, posteriorly, the gullet, stomach, small and large intestine, and rectum.

Glands. In addition to the alimentary canal proper, we find a number of digestive glands, varying in size and position, connected with the canal. A gland is a collection of cells which takes up materials from the blood and pours out the secretion as a fluid; such cells, together with the blood vessels and nerves passing to them, are held in place by a web of connective tissue.

It is the substances formed by these glands that cause the digestion of food. The substances secreted by the cells of the glands and poured out into the food tube act upon insoluble foods so as to change them to a soluble form.

STRUCTURE. The entire inner surface of the food tube is covered with a soft lining of mucous membrane. This is always moist because certain cells, called mucous cells, empty out their contents into the food tube, thus lubricating its inner surface. When a large number of cells which have the power to secrete or form fluids are collected together, the surface of the food tube may become indented; the little depression thus formed is a simple gland. If such a tube is greatly branched, with one common duct or tube connecting it with the inside surface of the food tube, it is then called a compound gland. we think of a very sour pickle or a delicious bit of candy, our mouth waters. This is caused by the action of certain nerves upon some of the gland cells in the mouth (salivaric glands); this results in the setting free of a fluid we call saliva. In case of stage fright, the secretion of saliva is prevented by the action of the nervous system, and the mouth becomes dry.

If

Structure of glands; 1, simple pit, surrounded by capillaries; 2, flaskshaped gland, with short duct; 3, 4, more complex glands, with longer ducts.

COMPARISON OF THE ALIMENTARY CANAL OF A FROG WITH THAT OF MAN.1 (Material - frogs preserved in alcohol or four per cent formol.) Notice the shape and size of the mouth when closed and when opened. Look for teeth. Feel with your finger the upper and lower jaws in the roof of the mouth. The prominent teeth on the roof of the mouth are known as the vomerine teeth. Notice the mucous membrane lining in the interior of the mouth. With a pencil or tweezers, find the baglike opening of the gullet through which food passes to the stomach. Do not

For more detailed work, see Hunter and Valentine, Manual, pp. 174-177.