522. _The quant.i.ty of air inhaled is modified by the capacity of the respiratory organs._ The necessity of voluminous lungs may he elucidated by the following experiment: Suppose a gill of alcohol, mixed with a gill of water, be put into a vessel having a square foot of surface, and over the vessel a membrane be tied, and that the water will evaporate in twenty-four hours. If the surface had been only six inches square, only one fourth of the water would have evaporated through the membrane in the given time. If the surface had been extended to two square feet, the water would have evaporated in twelve hours.

523. Apply this principle to the lungs: suppose there are two hundred feet of carbonic acid to be carried out of the system every twenty-four hours. This gas, in that time, will pa.s.s through a vesicular membrane of two thousand square feet. If the lungs were diminished in size, so that there would be only one thousand square feet of vesicular membrane, the amount of carbonic acid would not, and could not, be eliminated from the system. Under such circ.u.mstances, the blood would not be purified.

524. Again; suppose the two thousand square feet of membrane would transmit two hundred cubic feet of oxygen into the system every twenty-four hours. If it should be diminished one half, this amount of oxygen would not pa.s.s into the blood. From the above ill.u.s.trations we may learn the importance of well-developed chests and voluminous lungs; for, by increasing the size of the lungs, the oxygen is more abundantly supplied to the blood, and this fluid is more perfectly deprived of its carbon and hydrogen.

What does this hereditary transmission prove? 522. How is the necessity of voluminous lungs ill.u.s.trated? 525. How is this principle applied to the interchange of products in the lungs?

525. The chest is not only most expanded at its lower part, but the portion of the lungs that occupies this s.p.a.ce of the thoracic cavity contains the greater part of the air-cells; and, from the lower two thirds of the lungs the greatest amount of carbonic acid is abstracted from the blood, and the greatest amount of oxygen gas is conveyed into the circulating fluid. Hence, contracting the lower ribs is far more injurious to the health than diminishing the size of the upper part of the chest.

526. The question is often asked, Can the size of the chest and the volume of the lungs be increased, when they have been injudiciously compressed, or have inherited this unnatural form? The answer is in the affirmative. The means for attaining this end are, a judicious exercise of the lungs, by walking in the open air, reading aloud, singing, sitting erect, and fully inflating the lungs at each act of inspiration. If the exercise be properly managed and persevered in, it will expand the chest, and give tone and health to the important organs contained in it. But, if the exercise be ill-timed or carried to excess, the beneficial results sought will probably not be attained.

_Observation._ Scholars, and persons who sit much of the time, should frequently, during the day, breathe full and deep, so that the smallest air-cells may be fully filled with air. While exercising the lungs, the shoulders should be thrown back and the head held erect.

527. _The movement of the ribs and diaphragm is modified by the dress._ When the lungs are properly filled with air, the chest is enlarged in every direction. If any article of apparel is worn so tight as to prevent the full expansion of the chest and abdomen, the lungs, in consequence, do not receive air sufficient to purify the blood. The effect of firm, unyielding clothing, when worn tight, in preventing a due supply of air to the lungs, may be shown by the following ill.u.s.tration.

525. Why is it more injurious to contract the lower part of the chest than the upper? 526. How can the size of the chest be increased when it is contracted? Give the observation. 527. How is the movement of the ribs and diaphragm modified?

_Ill.u.s.tration._ If the diameter of a circle is three feet, the circ.u.mference will be nine feet. If the diameter is extended to four feet, the circ.u.mference will be increased to twelve feet. Should a tight band be thrown around a circle of nine feet, its diameter cannot be increased, for the circ.u.mference cannot be enlarged.

528. Any inelastic band, drawn closely around the lower part of the chest, or the abdomen, below the ribs, operates like the band in the preceding ill.u.s.tration, in restricting the movement of the ribs. When any article of dress encircles either the chest or abdomen, so as to prevent an increase of its circ.u.mference, it has an injudicious tendency, as it prevents the introduction of air in sufficient quant.i.ties to purify the blood. The question is not, How much restriction of the respiratory movements can be endured, and life continue? but, Does any part of the apparel restrict the movements? If it does, it is a violation of the organic laws; and though Nature is profuse in her expenditures, yet sooner or later, she sums up her account.

529. In determining whether the apparel is worn too tight, inflate the lungs, and, if no pressure is felt, no injurious effects need be apprehended from this cause. In testing the tightness of the dress, some persons will contract to the utmost the abdominal muscles, and thus diminish the size of the chest, by depressing the ribs; when this is done, the individual exclaims, "How loose my dress is!" This practice is both deceptive and ludicrous. A good test is, to put the hand on the chest below the arm; if there is no movement of the ribs during respiration, the apparel is too tight. The only reliable test, however, is a full inflation of the lungs.

How is the effect of unyielding clothing, when worn tight, ill.u.s.trated?

528. What effect has an inelastic band upon the lower part of the chest? What question is asked? 529. How can we determine whether the apparel is worn too tight?

_Observation._ Many individuals do not realize the small amount of force that will prevent the enlargement of the chest. This can be demonstrated by drawing a piece of tape tightly around the lower part of the chest of a vigorous adult, and confining it with the thumb and finger. Then endeavor fully to inflate the lungs, and the movement of the ribs will be much restricted.

530. _The position in standing and sitting influences the movement of the ribs and diaphragm._ When the shoulders are thrown back, and when a person stands or sits erect, the diaphragm and ribs have more freedom of motion, and the abdominal muscles act more efficiently; thus the lungs have broader range of movement than when the shoulders incline forward, and the body is stooping.

531. _Habit exercises an influence upon the range of the respiratory movements._ A person who has been habituated to dress loosely, and whose inspirations are full and free, suffers more from the tightness of a vest or waistband, than one, the range of movements of whose chest has long been subjected to tight lacing.

532. _The condition of the brain exercises a great influence upon respiration._ If the brain is diseased, or the mind depressed by grief, tormented by anxiety, or absorbed by abstract thought, the contractile energy of the diaphragm and muscles that elevate the ribs, is much diminished, and the lungs are not so fully inflated, as when the mind is influenced by joy or other exhilarating emotions. The depressing pa.s.sions likewise lessen the frequency of respiration. By the influence of these causes, the blood is but partially purified, and the whole system becomes enfeebled. Here we may see the admirable harmony between the different parts of the body, and the adaptation of all the functions to each other.

Give another test. How can the amount of pressure necessary to prevent the enlargement of the chest be demonstrated? 530. Show the effect of position on the movements of the ribs and diaphragm. 531. Show the effect of habit on the respiratory movements. 532. State the influence of the mind upon respiration.

533. As the quant.i.ty of air inhaled at each unimpeded inspiration in lungs of ample size, is about forty cubic inches, it follows, if the movement of the ribs and diaphragm is restricted by an enfeebled action of the respiratory muscles, or by any other means, the blood will not be perfectly purified. In the experiment, ( 522, 523,) suppose forty cubic inches of air must pa.s.s over the membrane twenty times every minute, and that this is the amount required to remove the vapor which arises from the membrane; if only half of this amount of air be supplied each minute, only one half as much water will be removed from the alcohol through the membrane in twenty-four hours; consequently, the alcohol would be impure from the water not being entirely removed.

534. Restrain the elevation of the ribs and depression of the diaphragm, so that the quant.i.ty of air conveyed into the lungs will be reduced to twenty cubic inches, when forty are needed, and the results will be as follows: Only one half of the carbonic acid will be eliminated from the system, and the blood will receive but one half as much oxygen as it requires. This fluid will then be imperfectly oxydated, and partially freed of its impurities. The impure blood will be returned to the left side of the heart, and the whole system will suffer from an infringement of organic laws.

533. Ill.u.s.trate the effect upon the blood when the respiratory muscles are enfeebled in their action. 534. Show how the blood is imperfectly purified by restricting the movements of the ribs and diaphragm.

535. _Scrofula, or consumption, frequently succeeds a depressed state of the nervous system._ These diseases arise from the deposition of tuberculous matter in different parts of the body. Those individuals who have met with reverses of fortune, in which character and property were lost, afford painful examples. Hundreds yearly die from the effect of depressed spirits, caused by disappointed hopes, or disappointed ambition.

_Ill.u.s.tration._ A striking instance of the effects of mental depression is related by Lnnec. In a female religious establishment in France, great austerities were practised; the mind was absorbed in contemplating the terrible truths of religion, and in mortifying the flesh. The whole establishment, in the s.p.a.ce of ten years, was several times depopulated--with the exception of the persons employed at the gate, in the kitchen, and garden--with that fatal disease, consumption. This inst.i.tution did not long continue, but was suppressed by order of the French government.

536. _The purity of the blood is influenced by the condition of the lungs._ When the bronchial tubes and air-cells have become partially impervious to air, from pressure upon the lungs, from fluids in the chest, from tumors, or from the consolidation of the cells and tubes from disease,--as inflammation, or the deposition of yellow, cheesy matter, called tubercles,--the blood will not be purified, even if the air is pure, the lungs voluminous, and the respiratory movements unrestricted, as the air cannot permeate the air-cells.

_Observations._ 1st. The twenty-three who escaped immediate death in the Black Hole of Calcutta were soon attacked with inflammation of the lungs, by which these organs were consolidated, and thus prevented the permeation of air into their cells. This disease of the lungs was caused by breathing vitiated air.

535. Mention some of the effects of mental depression upon the body.

What is related by Lnnec? 536. Does the condition of the lungs influence the purity of the blood? Mention some of the conditions that will impede the oxydation of blood in the lungs. What occurred to those persons who escaped death in the Black Hole of Calcutta?

2d. One of the precursory symptoms of consumption is the feeble murmur of respiration in the upper part of the lungs. This condition of these organs is produced by, or frequently follows, mental depression, the breathing of impure air, the stooping position in standing or sitting, and the restriction of the movements of the ribs and diaphragm.

3d. Persons asphyxiated by carbonic acid, water, strangling, or any noxious air, after resuscitation, are usually affected with coughs and other diseases of the lungs.

537. COLDS and COUGHS are generally induced by a chill, that produces a contraction of the blood-vessels of the skin; and the waste material, which should be carried from the body by the agency of the vessels of this membrane, is retained in the system, and a great portion of it is returned to the mucous membrane of the lungs. For such is the harmony established by the Creator, that if the function of any portion of the body is deranged, those organs whose offices are similar take on an increased action.

538. The waste material, that should have pa.s.sed through the many outlets of the skin, creates an unusual fulness of the minute vessels that nourish the mucous membrane of the bronchia; this induces an irritation of these vessels, which increases the flow of blood to the nutrient arteries of the lungs. There is, also, a thickening of the lining membrane of the lungs, caused by the repletion of the bronchial vessels of the mucous membrane; this impedes the pa.s.sage of air through the small bronchial tubes, and consequently the air-vesicles cannot impart a sufficient quant.i.ty of oxygen to purify the blood, and this fluid, imperfectly purified, does not pa.s.s with facility through the lungs. An additional obstacle to the free pa.s.sage of air into the lungs, is the acc.u.mulation of blood in the pulmonary vessels.

What is one of the precursory symptoms of consumption? How is this condition frequently produced? What diseases usually follow asphyxia by carbonic acid, water, strangling, &c.? 537. How are colds generally induced? 538. What effect has a common cold upon the mucous membrane of the lungs?

539. As colds and coughs are very generally treated by the "matrons"

of the community, or by the patient, the following suggestions may aid in directing a proper treatment: To effect a speedy cure, it is necessary to diminish the amount of fluid in the vessels of the lungs.

This can be effected in two ways: 1st. By diminishing the quant.i.ty of blood in the system; 2d. By diverting it from the lungs to the skin.

The first condition can be easily and safely affected, by abstaining from food, and drinking no more than a gill of fluid in twenty-four hours. As there is a continuous waste from the skin and other organs of the system, the quant.i.ty of blood by this procedure will be diminished, and the lungs relieved of the acc.u.mulated fluid.

540. The second condition can be accomplished by resorting to the warm or vapor bath. These and the common sweats will invite the blood from the lungs to the skin. By keeping up the action of the skin for a few hours, the lungs will be relieved. In some instances, emetics and cathartics are necessary; mucilages, as gum arabic or slippery-elm bark, would be good. After the system is relieved, the skin is more impressible to cold, and consequently requires careful protection by clothing. In good const.i.tutions, the first method is preferable, and generally sufficient without any medicine or "sweating."