In addition to removing dust particles and germs, other purposes are served by breathing through the nostrils. The warmth and moisture which the air receives in this way, prepare it for entering the lungs. Mouth breathing, on the other hand, looks bad and during sleep causes snoring.

The habit of nose breathing should be established early in life.(34)

*Cultivate Full Breathing.*-Many people, while apparently taking in sufficient air to supply their need for oxygen, do not breathe deeply enough to "freely ventilate the lungs." "Shallow breathing," as this is called, is objectionable because it fails to keep up a healthy condition of the entire lung surface. Portions of the lungs to which air does not easily penetrate fail to get the fresh air and exercise which they need.

As a consequence, they become weak and, by losing their "power of resistance," become points of attack in diseases of the lungs.(35) The breathing of each individual should receive attention, and where from some cause it is not sufficiently full and deep, the means should be found for remedying the defect.

*Causes of Shallow Breathing.*-Anything that impedes the free movement of air into the lungs tends to cause shallow breathing A drooping of the back or shoulders and a curved condition of the spinal column, such as is caused by an improper position in sitting, interfere with the free movements of the ribs and are recognized causes. Clothing also may impede the respiratory movements and lead to shallow breathing. If too tight around the chest, clothing interferes with the elevation of the ribs; and if too tight around the waist, it prevents the depression of the diaphragm. Other causes of shallow breathing are found in the absence of vigorous exercise, in the leading of an indoor and inactive life, in obstructions in the nostrils and upper pharynx, and in the lack of attention to proper methods of breathing.

To prevent shallow breathing one should have the habit of sitting and standing erect. The clothing must not be allowed to interfere with the respiratory movements. The taking of exercise sufficiently vigorous to cause deep and rapid breathing should be a common practice and one should spend considerable time out of doors. If one has a flat chest or round shoulders, he should strive by suitable exercises to overcome these defects. Obstructions in the nostrils or pharynx should be removed.

*Breathing Exercises.*-In overcoming the habit of shallow breathing and in strengthening the lungs generally, the practicing of occasional deep breathing has been found most valuable and is widely recommended. With the hands on the hips, the shoulders drawn back and _down_, the chest pushed upward and forward, and the chin slightly depressed, draw the air slowly through the nostrils until the lungs are _completely_ full. After holding this long enough to count three slowly, expel it quickly from the lungs.

Avoid straining. To get the benefit of pure air, it is generally better to practice deep breathing out of doors or before an open window.

By combining deep breathing with simple exercises of the arms, shoulders, and trunk much may be done towards straightening the spine, squaring the shoulders, and overcoming flatness of the chest. Though such movements are best carried on by the aid of a physical director, one can do much to help himself. One may safely proceed on the principle that slight deformities of the chest, spine, and shoulders are corrected by gaining and keeping the natural positions, and may employ any movements which will loosen up the parts and bring them where they naturally belong.(36)

*Serious Nature of Colds.*-That many cases of consumption have their beginning in severe colds (on the lungs) is not only a matter of popular belief, but the judgment also of physicians. Though the cold is a different affection from that of consumption, it may so lower the vitality of the body and weaken the lung surfaces that the germs of consumption find it easy to get a start. On this account a cold on the chest which does not disappear in a few days, but which persists, causing more or less coughing and pain in the lungs, must be given serious consideration.(37) The usual home remedies failing to give relief, a physician should be consulted. It should also be noted that certain diseases of a serious nature (pneumonia, diphtheria, measles, etc.) have in their beginning the appearance of colds. On this account it is wise not only to call a physician, but to call him early, in severe attacks of the lungs.

Especially if the attack be attended by difficult breathing, fever, and a rapid pulse is the case serious and medical advice necessary.

*Ventilation.*-The process by which the air in a room is kept fresh and pure is known as ventilation. It is a double process-that of bringing fresh air into the room and that of getting rid of air that has been rendered impure by breathing (38) or by lamps. Outdoor air is usually of a different temperature (colder in winter, warmer in summer) from that indoors, and as a consequence differs from it slightly in weight. On account of this difference, suitable openings in the walls of buildings induce currents which pa.s.s between the rooms and the outside atmosphere even when there is no wind. In winter care must be taken to prevent drafts and to avoid too great a loss of heat from the room. A cold draft may even cause more harm to one in delicate health than the breathing of air which is impure. To ventilate a room successfully the problem of preventing drafts must be considered along with that of admitting the fresh air.

[Fig. 46]

Fig. 46-Window adjusted for ventilation without drafts.

The method of ventilation must also be adapted to the construction of the building, the plan of heating, and the condition of the weather. Specific directions cannot be given, but the following suggestions will be found helpful in ventilating rooms where the air is not warmed before being admitted:

1. _Introduce, the air through many small openings_ rather than a few large ones. If the windows are used for this purpose, raise the lower sash and drop the upper one _slightly_ for _several_ windows, varying the width to suit the conditions (Fig. 46). By this means sufficient air may be introduced without causing drafts.

2. _Introduce the air at the warmest portions of the room._ The air should, if possible, be warmed before reaching the occupants.

3. If the wind is blowing, _ventilate princ.i.p.ally on the sheltered side of the house_.

Ample provision should be made for fresh air in sleeping rooms, and here again drafts must be avoided. Especially should the bed be so placed that strong air currents do not pa.s.s over the sleeper. In schoolhouses and halls for public gatherings the means for efficient ventilation should, if possible, be provided in the general plan of construction and method of heating.

[Fig. 47]

Fig. 47-*Artificial respiration* as a laboratory experiment. Expiration.

p.r.o.ne-posture method of Schaffer.

*Artificial Respiration.*-When natural breathing is temporarily suspended, as in partial drowning, or when one has been overcome by breathing some poisonous gas, the saving of life often depends upon the prompt application of artificial respiration. This is accomplished by alternately compressing and enlarging the thorax by means of variable pressure on the outside, imitating the natural process as nearly as possible. Following is the method proposed by Professor E.A. Schaffer of England, and called by him "the _p.r.o.ne-posture_ method of artificial respiration":

The patient is laid face downward with an arm bent under the head, and _intermittent_ pressure applied vertically over the shortest ribs. The pressure drives the air from the lungs, both by compressing the lower portions of the chest and by forcing the abdominal contents against the diaphragm, while the elastic reaction of the parts causes fresh air to enter (Figs. 47 and 48). "The operator kneels or squats by the side of, or across the patient, places his hands over the lowest ribs and swings his body backward and forward so as to allow his weight to fall vertically on the wrists and then to be removed; in this way hardly any muscular exertion is required.... The pressure is applied gradually and slowly, occupying some three seconds; it is then withdrawn during two seconds and again applied; and so on some twelve times per minute."(39)

[Fig. 48]

Fig. 48-Artificial respiration. Inspiration.

The special advantages of the p.r.o.ne-posture method over others that have been employed are: I. It may be applied by a single individual and fora long period of time without exhaustion. 2. It allows the mucus and water (in case of drowning) to run out of the mouth, and causes the tongue to fall forward so as not to obstruct the pa.s.sageway. 3. It brings a sufficient amount of air into the lungs.(40)

While applying artificial respiration, the heat of the body should not be allowed to escape any more than can possibly be helped. In case of drowning, the patient should be wrapped in dry blankets or clothing, while bottles of hot water may be placed in contact with the body. The circulation should be stimulated, as may be done by rubbing the hands, feet, or limbs in the direction of the flow of the blood in the veins.

*Tobacco Smoke and the Air* Pa.s.sages.-Smoke consists of minute particles of unburnt carbon, or soot, such as collect in the chimneys of fireplaces and furnaces. If much smoke is taken into the lungs, it irritates the delicate linings and tends to clog them up. Tobacco smoke also contains the poison nicotine, which is absorbed into the blood. For these reasons the cigarette user who inhales the smoke does himself great harm, injuring his nervous system and laying the foundation for diseases of the air pa.s.sages. The practice of smoking indoors is likewise objectionable, since every one in a room containing the smoke is compelled to breathe it.

*Alcohol and Diseases of the Lungs.*-Pneumonia is a serious disease of the lungs caused by germs. The attacks occur as a result of exposure, especially when the body is in a weakened condition. A noted authority states that "alcoholism is perhaps the most potent predisposing cause" of pneumonia.(41) A person addicted to the use of alcohol is also less likely to recover from the disease than one who has avoided its use, a result due in part to the weakening effect of alcohol upon the heart. The congestion of the lungs in pneumonia makes it very difficult for the heart to force the blood through them. The weakened heart of the drunkard gives way under the task.

The statement sometimes made that alcohol is beneficial in pulmonary tuberculosis is without foundation in fact. On the other hand, alcoholism is a recognized cause of consumption. Some authorities claim that this disease is more frequent in heavy drinkers than in those of temperate habits, in the proportion of about three to one, and that possibly half of the cases of tuberculosis are traceable to alcoholism.(42)

*The Outdoor Cure for Lung Diseases*-Among the many remedies proposed for consumption and kindred diseases, none have proved more beneficial, according to reports, than the so-called "outdoor" cure. The person having consumption is fed plentifully upon the most nourishing food, and is made to spend practically his entire time, including the sleeping hours, _out of doors_. Not only is this done during the pleasant months of summer, but also during the winter when the temperature is below freezing. Severe exposure is prevented by overhead protection at night and by sufficient clothing to keep the body warm. The abundant supply of pure, cold air toughens the lungs and invigorates the entire body, thereby enabling it to throw off the disease.

The success attending this method of treating consumptives suggests the proper mode of strengthening lungs that are not diseased, but simply weak.

The person having weak lungs should spend as much time as he conveniently can out of doors. He should provide the most ample ventilation at night and have a sleeping room to himself. He should practice deep breathing exercises and partake of a nourishing diet. While avoiding prolonged chilling and other conditions liable to induce colds, he should take advantage of every opportunity of exposing himself fully and freely to the outside atmosphere.

*Summary.*-The purpose of respiration is to bring about an exchange of gases between the body and the atmosphere. The organs employed for this purpose, called the respiratory organs, are adapted to handling materials in the _gaseous_ state, and are operated in accordance with principles governing the movements of the atmosphere. By alternately increasing and diminishing the thoracic s.p.a.ce, air is made to pa.s.s between the outside atmosphere and the interior of the lungs. Finding its way into the smallest divisions of the lungs, called the alveoli, the air comes very near a large surface of blood. By this means the carbon dioxide diffuses out of the blood, and the free oxygen enters. Through the combined action of the organs of respiration and the organs that move the blood and the lymph, the cells in all parts of the body are enabled to exchange certain gaseous materials with the outside atmosphere.

[Fig. 49]

Fig. 49-Model for demonstrating the lungs.

*Exercises.-*1. How does air entering the lungs differ in composition from air leaving the lungs? What purposes of respiration are indicated by these differences?

2. Name the divisions of the lungs.

3. Trace air from the outside atmosphere into the alveoli. Trace the blood from the right ventricle to the alveoli and back again to the left auricle.

4. How does the movement of air into and from the lungs differ from that of the blood through the lungs with respect to (_a_) the direction of the motion. (_b_) the causes of the motion, and (_c_) the tubes through which the motion takes place?

5. How are the air pa.s.sages kept clean and open?

6. Describe the pleura. Into what divisions does it separate the thoracic cavity?

7. Describe and name uses of the diaphragm.

8. If 30 cubic inches of air are pa.s.sed into the lungs at each inspiration and .05 of this is retained as oxygen, calculate the number of cubic feet of oxygen consumed each day, if the number of inspirations be 18 per minute.

9. Find the _weight_ of a day's supply of oxygen, as found in the above problem, allowing 1.3 ounces as the weight of a cubic foot.

10. Make a study of the hygienic ventilation of the schoolroom.

11. Give advantages of full breathing over shallow breathing.

12. How may a flat chest and round shoulders be a cause of consumption?

How may these deformities be corrected?