Chapter XVI

.)

11 Coagulation is not confined to the blood. The white of an egg coagulates when heated and when acted upon by certain chemicals, and the clabbering of milk also is a coagulation.

12 If the blood be stirred or "whipped" while it is coagulating, the clot may be broken up and the fibrin separated as fast as it forms. The blood which then remains consists of serum and corpuscles and will not coagulate. It is known as "defibrinated" blood.

13 Certain substances, called _opsonins_, have recently been shown to exist in the plasma, that aid the white corpuscles in their work of destroying germs. The opsonins appear to act in such a manner as to weaken the germs and make them more susceptible to the attacks of the white corpuscles.

14 Some of the changes in the blood are very closely related to our everyday habits and inclinations. For example, a lack of nourishment in the blood causes hunger and this leads to the taking of food. If the fluids of the body become too dense, a feeling of thirst is aroused which prompts one to drink water.

15 Metchnikoff, _The New Hygiene_.

16 A physiological salt solution is prepared by dissolving .6 of a gram of common salt in 100 cc. of distilled water or pure cistern water. This solution, having the same density as the plasma of the blood, does not act injuriously upon the corpuscles.

17 The term "circulation" literally means moving in a circle. While the blood does not move through the body in a circle, the term is justified by the fact that the blood flows out continually from a single point, the heart, and to this point is continually returning.

18 The heart at first glance seems to bear little resemblance to the pumps in common use. When it is remembered, however, that any contrivance which moves a fluid by varying the size of a cavity is a pump, it is seen that not only the heart, but the chest in breathing and also the mouth in sucking a liquid through a tube, are pumps in principle. The ordinary syringe bulb illustrates the class of pumps to which the heart belongs. (See Practical Work.)

19 The contraction of the heart is known as the _systole_ and its relaxation as the _diastole_. The systole plus the diastole forms the so-called "cardiac cycle" (Fig. 18). This consists of (1) the contraction of the auricles, (2) the contraction of the ventricles, and (3) the period of rest. The heart systole includes the contraction of both the auricles and the ventricles.

20 Martin, _The Human Body_.

21 The pressure maintained by the left ventricle has been estimated to be nearly three and one half pounds to the square inch--a pressure sufficient to sustain a column of water eight feet high. The pressure maintained by the right ventricle is about one third as great. In maintaining this pressure the heart does a work equal to about one two-hundredth of a horse power.

22 The location of the heart in the thoracic cavity causes movements of the chest walls to draw blood into the right auricle for the same reason that they "draw" air into the lungs.

23 Active exercise through short intervals, followed by periods of rest, such as the exercise furnished by climbing stairs, or by short runs, is considered the best means of strengthening the heart.

24 Nosebleed in connection with any kind of severe sickness should receive prompt attention, since a considerable loss of blood when the body is already weak may seriously delay recovery.

25 Newton, _Practical Hygiene_.

26 On account of its position in the body, the lymph is not easily collected for examination. Still, nearly every one will recall some experience that has enabled him to see lymph. The liquid in a water blister is lymph, and so also is the liquid which oozes from the skin when it is scraped or slightly scratched. Swelling in any part of the body is due to the accumulation of lymph at that place.

27 In certain small animals of the lowest types a single liquid, serving as a medium of exchange between the cells and the body surface, supplies all the needs of the organism. In larger animals, however, where materials have to be moved from one part of the cell group to another, a portion of the nutrient fluid is used for purposes of transportation. This is confined in channels where it is set in motion by suitable organs. The portion which remains outside of the channels then transfers material between the cells, on the one hand, and the moving liquid, on the other.

28 Surgeons in opening veins near the thoracic cavity have to be on their guard to prevent air from being sucked into them, thereby causing death.

29 Oxygen forms about 21 per cent of the atmosphere, nitrogen about 78 per cent, carbon dioxide about .03 per cent, and the recently discovered element argon about 1 per cent. The oxygen is in a _free_, or uncombined, condition--the form in which it can be used in the body.

30 The peculiar work devolving upon the organs of respiration necessitates a special plan of construction--one adapted to the properties of the atmosphere. Being concerned in the movement of air, a gaseous substance, they will naturally have a structure different from the organs of circulation which move a liquid (the blood). All the organs of the body are adapted by their structure to the work which they perform.

31 In ordinary inspirations the force that causes the air to move through the passages is scarcely an ounce to the square inch, while in forced inspirations it does not exceed half a pound. On this account the closing of any of the air passages by pressure, or by the presence of foreign substances, would keep the air from reaching some part of the lungs.

32 Coughing, which is a forceful expulsion of air, has for its purpose the ejection of foreign substances from the throat and lungs. Sneezing, on the other hand, has for its purpose the cleansing of the nostrils. In coughing, the air is expelled through the mouth, while in sneezing it is expelled through the nostrils.

33 The amount of dust suspended in what we ordinarily think of as pure air is shown when a beam of direct sunlight enters an otherwise darkened room.

34 Some children find it difficult to breathe through the nostrils on account of growths (called adenoids) in the upper pharynx. Such children should have medical attention. The removal of these growths not only improves the method of breathing, but in many instances causes a marked improvement in the general health and personal appearance.

35 The weakest portions of the lungs appear to be the tiny lobes at the top. As they occupy the part of the thorax most difficult to expand, air penetrates them much less freely than it does the lobes below. In most cases of consumption (some authorities give as high as eighty per cent), the upper lobes are the first to be affected. Flat chests and round shoulders, by increasing this natural difficulty in breathing, have long been recognized as causes which predispose to consumption.

36 The following exercise, from Dudley A. Sargent's _Health, Strength, and Power_, will be found most beneficial: "Stand with the feet together, face downward, arms extended downward, and backs of the hands touching. Raise the hands, arms, and elbows, keeping the backs of the hands together until they pass the chest and face. Then continue the movement upward, until the hands separate above the head with the face turned upward, when they should be brought downward and outward in a large circle to the starting point. Begin to inhale as the arms are raised and take in as much air as possible by the time the hands are above the head, then allow the breath to go out slowly as the arms descend."

37 Colds may frequently be broken up at their beginning by taking a prolonged _hot_ bath and going to bed. After getting a start, however, they run a course of a few days, a week, or longer, depending upon the natural vigor of the individual and the care which he gives his body during the time. In throwing off a cold, the following suggestions will be found helpful:

1. Dress warmly (without overdoing it) and avoid getting chilled. 2. Diminish the usual amount of work and increase the period for sleep. If very weak, stay in bed. Save the energy for throwing off the cold. 3. If able to be about, spend considerable time in light exercise out of doors, but avoid getting chilled. 4. Keep the bowels

## active, taking a cathartic if necessary. 5. To relieve pain in the

chest, apply a mustard plaster or a flannel cloth moistened with some irritating substance, such as turpentine or a mixture of equal parts of kerosene and lard. Keep up a mild irritation until the pain is relieved, but avoid blistering.

38 Not only do the lungs remove oxygen from the air and add carbon dioxide to it, but they separate from the body considerable moisture and, according to some authorities, a small amount of an impurity referred to as "animal matter." Odors also arise from the skin, teeth, and clothing which, if not dangerous to the health, are offensive to the nostrils. If on going into a room such odors are detected, the ventilation is not sufficient. This is said to be a reliable test.

39 E.A. Schaffer, "Artificial Respiration in its Physiologic Aspects," _The Journal of the American Medical Association_, September, 1908.

40 Testing the prone-posture method by suitable apparatus, Professor Schaffer has found it capable of introducing more air per minute into the lungs than any of the other methods of artificial respiration, and more even than is introduced by ordinary breathing.

41 Osier, _The Principles and Practice of Medicine_.

42 Huber, _Consumption and Civilization_.

43 To prepare limewater some small lumps of _fresh_ lime (either slacked or unslacked) are added to a large bottle of water and thoroughly shaken. This is put aside until the lime all settles to the bottom and the water above is perfectly clear. This is now ready for use and may be poured off as needed. When the supply is exhausted add more water and shake again.

44 An _element_ is a single kind of matter. Those substances are classed as elements which cannot be separated into different kinds of matter. Two or more elements combined in definite proportions by weight form a _compound_. The elements are few in number, only about eighty being known. Compounds, on the other hand, are exceedingly numerous.

45 The term _energy_, as used here, has the same general meaning as the word _power_. See