Chapter IV: ABSORPTION is performed in two ways, by the veins, and the (3)

THE PHYSIOLOGICAL EFFECT of its prolonged use is very marked. The appetite becomes capricious. The secretions are unnatural. Nausea and flatulency often ensue. Then the nervous system is involved. The heart is affected. Sleep, instead of responding to the drug, as at first, is broken and disturbed. The eyesight fails. The circulation is enfeebled, and the pulse becomes weak, rapid, and irregular. There is a tendency to fainting and to difficult respiration. Sometimes the impoverished blood induces a disease resembling scurvy, the ends of the fingers ulcerate, and the face is disfigured by blotches. An excessive dose may result in death.

Prolonged habitual use of chloral hydrate tends to debase the mind and morals of the subject in the same manner as indulgence in alcohol, ether, or chloroform.

5. CHLOROFORM.

CHLOROFORM is an artificial product generally obtained, by distillation, from a mixture of chloride of lime, water, and alcohol. It was discovered in 1831 by Samuel Guthrie, of Sackett's Harbor, New York. It is a colorless, transparent volatile liquid, with a strong ethereal odor.

PHYSIOLOGICAL EFFECT.--Chloroform is a powerful anæsthetic, which, when inhaled, causes a temporary paralysis of the nervous system, and thus a complete insensibility to pain. There is great peril attending its use, even in the hands of the most skillful and experienced practitioners. It is sometimes prescribed by a physician, and afterward (as in the case of laudanum, morphine, and chloral) the sufferer, charmed with the release from pain and the peaceful slumber secured, buys the Lethean liquid for himself. Its use soon becomes an apparent necessity. The craving for the narcotic at a stated time is almost irresistible. The patient, compelled to give up the use of chloroform, will demand, entreat, pray for another dose, in a heartrending manner, never to be forgotten. Paleness and debility, the earliest symptoms, are followed by mental prostration. Familiarity with this dangerous drug begets carelessness, and its victims are frequently found dead in their beds, with the handkerchief from which they inhaled the volatile poison clutched in their lifeless hands.

6. COCAINE.

Cocaine is an alkaloid prepared from the erythroxylon coca, a shrub, five or six feet high, found wild in the mountainous regions of Ecuador and Peru, where it is also cultivated by the natives. The South American Indians, for centuries, have chewed coca leaves as a stimulant, but the highly poisonous principle, now called cocaine, to which the plant owes its peculiar effects, was not discovered till 1859. Within a few years this drug has come into favor as an agent to produce local anæsthesia, and has proved exceedingly valuable in surgical operations upon the eye and other sensitive organs. It has already, however, been diverted from its legitimate use as a benefaction, and to the other evils of the day is now added the "cocaine habit," which is, perhaps, even more dangerous and difficult to abandon than either the alcohol or the opium habit.

PHYSIOLOGICAL EFFECT.--Applied locally, cocaine greatly lessens and even annihilates pain. Taken internally, it acts as a powerful stimulant to the nervous system, its physiological action being similar to that of theine (p. 170), caffeine, and theobromine. Used hypodermically, its immediate effect, says one to whom it was thus administered, is to cause "great pallor of countenance, profuse frontal perspiration, sunken eyes, enlarged pupils, lessened sensitiveness of the cornea and conjunctiva, lowered arterial tension, and a feeble pulse and heart beat. Under its influence I could not reason. Everything seemed to run through my brain, and in vain I summoned all my will power to overcome an overwhelming sleepiness." A few doses of this drug will in some persons produce temporary insanity. Used to excess, it leads to permanent madness or idiocy. "Cocaine," says a writer in the _Medical Review_, "is a dangerous therapeutic toy not to be used as a sensational plaything. If it should come into as general use as the other intoxicants of its class, it will help to fill the asylums, inebriate and insane."

PRACTICAL QUESTIONS.

1. Why is the pain of incipient hip disease frequently felt in the knee?

2. Why does a child require more sleep than an aged person?

3. When you put your finger in the palm of a sleeping child, why will he grasp it?

4. How may we strengthen the brain?

5. What is the object of pain?

6. Why will a blow on the stomach sometimes stop the heart?

7. How long will it take for the brain of a man six feet high to receive news of an injury to his foot, and to reply?

8. How can we grow beautiful?

9. Why do intestinal worms sometimes affect a child's sight?

10. Is there any indication of character in physiognomy?

11. When one's finger is burned, where is the ache?

12. Is a generally closed parlor a healthful room?

13. Why can an idle scholar read his lesson and at the same time count the marbles in his pocket?

14. In amputating a limb, what part, when divided, will cause the keenest pain?

15. What is the effect of bad air on nervous people?

16. Is there any truth in the proverb that "he who sleeps dines"?

17. What does a high, wide forehead indicate?

18. How does indigestion frequently cause a headache?

19. What is the cause of one's foot being "asleep"? [Footnote: Here the nervous force is prevented from passing by compression. Just how this is done, or what is kept from passing, we can not tell. If a current of electricity were moving through a rubber tube full of mercury, a slight squeeze would interrupt it. These cases may depend on the same general principle, but we can not assert it.--HUXLEY. The tingling sensation caused by the compression is transferred to the foot, whence the nerve starts.]

20. When an injury to the nose has been remedied by transplanting skin from the forehead, why is a touch to the former felt in the latter?

21. Are closely curtained windows healthful?

22. Why, in falling from a height, do the limbs instinctively take a position to defend the important organs?

23. What causes the pylorus to open and close at the right time?

24. Why is pleasant exercise most beneficial?

25. Why does grief cause one to lose his appetite?

26. Why should we never study directly after dinner?

27. What produces the peristaltic movement of the stomach?

28. Why is a healthy child so restless and full of mischief?

29. Why is a slight blow on the back of a rabbit's neck fatal?

30. Why can one walk and carry on a conversation at the same time?

31. What are the dangers of overstudy?

32. What is the influence of idleness upon the brain?

33. State the close relation which exists between physical and mental health and disease.

34. In what consists the value of the power of habit?

35. How many pairs of nerves supply the eye?

36. Describe the reflex actions in reading aloud.

37. Under what circumstances does paralysis occur?

38. If the eyelids of a profound sleeper were raised, and a candle brought near, would the iris contract?

39. How does one cough in his sleep?

40. Give illustrations of the unconscious action of the brain.

41. Is chewing tobacco more injurious than smoking?

42. Ought a man to retire from business while his faculties are still unimpaired?

43. Which is the more exhaustive to the brain, worry or severe mental application?

44. Is it a blessing to be placed beyond the necessity for work?

45. Show how anger, hate, and the other degrading passions are destructive to the brain. [Footnote: "One of the surest means for keeping the body and mind in perfect health consists in learning to hold the passions in subservience to the reasoning faculties. This rule applies to every passion. Man, distinguished from all other animals by the peculiarity that his reason is placed above his passions to be the director of his will, can protect himself from every mere animal degradation resulting from passionate excitement. The education of the man should be directed not to suppress such passions as are ennobling, but to bring all under governance, and specially to subdue those most destructive passions, anger, hate, and fear."]

46. Are not amusements, to repair the waste of the nervous energy, especially needed by persons whose life is one of care and toil?

47. Is not severe mental labor incompatible with a rapidly growing body?

48. How shall we induce the system to perform all its functions regularly

49. How does alcohol interfere with the action of the nerves?

50. What is the general effect of alcohol upon the character?

51. Does alcohol tend to produce clearness and vigor of thought?

52. What is the general effect of alcohol on the muscles?

53. Does alcohol have any effect on the bones? The skin?

54. What is the cause of the "alcoholic chill"?

55. Show how alcohol tends to develop man's lower, rather than his higher, nature.

56. When we wish really to strengthen the brain, should we use alcohol?

57. Why is alcohol used to preserve anatomical specimens?

58. What is meant by an inherited taste for liquor?

59. Ought a person to be punished for a crime committed during intoxication?

60. Should a boy ever smoke?

61. To what extent are we responsible for the health of our body?

62. Why does alcohol tend to collect in the brain?

63. Does the use of alcohol tend to increase crime and poverty?

VIII.

THE SPECIAL SENSES.

"See how yon beam of seeming white Is braided, out of seven-hued light; Yet in those lucid globes no ray By any chance shall break astray. Hark, how the rolling surge of sound, Arches and spirals circling round, Wakes the hush'd spirit through thine ear With music it is heaven to hear."

HOLMES.

"Let us remember that if we get a glimpse of the details of natural phenomena, and of those movements which constitute life, it is not in considering them as a whole, but in analyzing them as far as our limited means will permit. In the vibrations of the globe of air which surrounds our planet, as in the undulations of the ether which fills the immensity of space, it is always by molecules which are intangible for us, put in motion by nature, always by the infinitely little, that she acts in exciting the organs of sense, and she has modeled these organs in a proportion which enables them to partake in the movement which she impresses upon the universe. She can paint with equal facility on a fraction of a line of space on the retina, the grandest landscape or the nervelets of a rose leaf; the celestial vault on which Sirius is but a luminous point, or the sparkling dust of a butterfly's wing; the roar of the tempest, the roll of thunder, the echo of an avalanche, find equal place in the labyrinth whose almost imperceptible cavities seem destined to receive only the most delicate sounds."

_ _ | 1. THE TOUCH...| 1. Description of the Organ. | |_2. Its Uses. | _ | 2. THE TASTE...| 1. Description of the Organ. | |_2. Its Uses. | _ | 3. THE SMELL...| 1. Description of the Organ. | |_2. Its Uses. | _ _ | | 1. Description of the | a. _External Ear._ | | Organ...............| b. _Middle Ear._ | 4. THE HEARING.| |_c. _Internal Ear._ | | 2. How we Hear | |_3. Hygiene of the Ear. | _ | | 1. Description of the Organ. | | 2. Eyelids, and Tears. | | 3. Structure of the Retina. |_5. THE SIGHT...| 4. How we see. | 5. The Use of the Crystalline Lens. | 6. Near and Far Sight. | 7. Color Blindness. |_8. Hygiene of the Eyes.

THE SPECIAL SENSES

1. TOUCH.

DESCRIPTION.--Touch is sometimes called the "common sense," since its nerves are spread over the whole body. It is most delicate, however, in the point of the tongue and the tips of the fingers. The surface of the cutis is covered with minute, conical projections called _papillæ_ (Fig. 24). [Footnote: In the palm of the hand, where there are at least twelve thousand in a square inch, we can see the fine ridges along which they are arranged.] Each one of these papillæ contains its tiny nerve twigs, which receive the impression and transmit it to the brain, where the perception is produced.

USES.--Touch is the first of the senses used by a child. By it we obtain our idea of solidity, and throughout life rectify all other sensations. Thus, when we see anything curious, our first desire is to handle it.

The sensation of touch is generally relied upon, yet, if we hold a marble in the manner shown in Fig. 57, it will seem like two marbles; and if we touch the fingers thus crossed to our tongue, we shall seem to feel two tongues. Again, if we close our eyes and let another person move one of our fingers over a plane surface, first lightly, then with greater pressure, and then lightly again, we shall think the surface concave.

FIG. 57.

This organ is capable of wonderful cultivation. The physician acquires by practice the _tactus eruditus_, or learned touch, which is often of great service, while the delicacy of touch possessed by the blind almost compensates the loss of the absent sense. [Footnote: The sympathy between the different organs shows how they all combine to make a home for the mind. When one sense fails, the others endeavor to remedy the defect. It is touching to see how the blind man gets along without eyes, and the deaf without ears. Cuthbert, though blind, was the most efficient polisher of telescopic mirrors in London. Saunderson, the successor of Newton as professor of mathematics at Cambridge, could distinguish between real and spurious medals. There is an instance recorded of a blind man who could recognize colors. The author knew one who could tell when he was approaching a tree, by what he described as the "different feeling of the air."] (See p. 346.)

2. TASTE.

DESCRIPTION.--This sense is located in the papillæ of the tongue and palate. These papillaæ start up when tasting, as you can see by placing a drop of vinegar on another person's tongue, or your own before a mirror. The velvety look of this organ is given by hair-like projections of the cuticle upon some of the papillæ. They absorb the liquid to be tasted, and convey it to the nerves. [Footnote: An insoluble substance is therefore tasteless.] The back of the tongue is most sensitive to salt and bitter substances, and, as this part is supplied by the ninth pair of nerves (Fig. 56), in sympathy with the stomach, such flavors, by sympathy, often produce vomiting. The edges of the tongue are most sensitive to sweet and sour substances, and as this part is supplied by the fifth pair of nerves, which also goes to the face, an acid, by sympathy, distorts the countenance.

FIG. 58.

THE USE OF THE TASTE was originally to guide in the selection of food; but this sense has become so depraved by condiments and the force of habit that it would be a difficult task to tell what are one's natural tastes.

3. SMELL. [Footnote: The sense of smell is so intimately connected with that of taste that we often fail to distinguish between them. Garlic, vanilla, coffee and various spices, which seem to have such distinct taste, have really a powerful odor, but a feeble flavor.]

DESCRIPTION.--The nose, the seat of the sense of smell, is composed of cartilage covered with muscles and skin, and joined to the skull by small bones. The nostrils open at the back into the pharynx, and are lined by a continuation of the mucous membrane of the throat. The olfactory nerves (first pair, Fig. 55) enter through a sieve-like, bony plate at the roof of the nose, and are distributed over the inner surface of the two olfactory chambers. (See p. 346.) The object to be smelled need not touch the nose, but tiny particles borne on the air enter the nasal passages. [Footnote: Three quarters of a grain of musk placed in a room will cause a powerful smell for a considerable length of time without any sensible diminution in weight, and the box in which musk has been placed retains the perfume for almost an indefinite period. Haller relates that some papers which had been perfumed by a grain of ambergris, were still very odoriferous after a lapse of forty years. Odors are transported by the air to a considerable distance. A dog recognizes his master's approach by smell even when he is far away; and we are assured by navigators that the winds bring the delicious odors of the balmy forests of Ceylon to a distance of ten leagues from the coast. Even after making due allowance for the effects of the imagination, it is certain that odors act as an excitant on the brain, which may be dangerous when long continued. They are especially dreaded by the Roman women. It is well known that in ancient times the women of Rome indulged in a most immoderate use of baths and perfumes; but those of our times have nothing in common with them in this respect; and the words of a lady are quoted, who said on admiring an artificial rose, "It is all the more beautiful that it has no smell." We are warned by the proverb not to discuss colors or tastes, and we may add odors also. Men and nations differ singularly in this respect. The Laplander and the Esquimaux find the smell of fish oil delicious. Wrangel says his compatriots, the Russians, are very fond of the odor of pickled cabbage, which forms an important part of their food; and asaftida, it is said, is used as a condiment in Persia, and, in spite of its name, there are persons who do not find its odor disagreeable any more than that of valerian.--_Wonders of the Human body_.]

FIG. 59.

THE USES of the sense of smell are to guide us in the choice of our food, and to warn us against bad air, and unhealthy localities. (See p. 348.)

4. HEARING.

DESCRIPTION.--The ear is divided into the _external_, _middle_, and _internal_ ear.

1. _The External Ear_ is a sheet of cartilage curiously folded for catching sound. The auditory canal, _B_, or tube of this ear trumpet, is about an inch long. Across the lower end is stretched _the membrane of the tympanum_ or drum, which is kept soft by a fluid wax.

FIG. 60.

2. _The Middle Ear_ is a cavity, at the bottom of which is the Eustachian tube, _G_, leading to the mouth. Across this chamber hangs a chain of three singular little bones, _C_, named from their shape the _hammer_, the _anvil_, and the _stirrup_. All together these tiny bones weigh only a few grains, yet they are covered by a periosteum, are supplied with blood vessels, and they articulate with perfect joints (one a ball-and-socket, the other a hinge), having synovial membranes, cartilages, ligaments, and muscles.

3. _The Internal Ear_, or labyrinth, as it is sometimes called from its complex character, is hollowed out of the solid bone. In front, is the vestibule or antechamber, _A_, about as large as a grain of wheat; from it open three _semicircular canals_, _D_, and the winding stair of the _cochlea_, or snail shell, _E_. Here expand the delicate fibrils of the auditory nerve. Floating in the liquid which fills the labyrinth is a little bag containing hair-like bristles, fine sand, and two ear stones (_otoliths_). All these knocking against the ends of the nerves, serve to increase any impulse given to the liquid in which they lie. Finally, to complete this delicate apparatus, in the cochlea are minute tendrils, named the fibers of Corti, from their discoverer. These are regularly arranged,--the longest at the bottom, and the shortest at the top. Could this spiral plate, which coils two and a half times around, be unrolled and made to stand upright, it would form a beautiful microscopic harp of three thousand strings. If it were possible to strike these cords as one can the keyboard of a piano, he could produce in the mind of the person experimented upon every variety of tone which the ear can distinguish.

HOW WE HEAR.--Whenever one body strikes another in the air, waves are produced, just as when we throw a stone into the water a series of concentric circles surrounds the spot where it sinks. These waves of air strike upon the membrane. This vibrates, and sends the motion along the chain of bones in the middle ear to the fluids of the labyrinth. Here bristles, sand, and stones pound away, and the wondrous harp of the cochlea, catching up the pulsations, [Footnote: The original motion is constantly modified by the medium through which it passes. The bristles, otoliths, and Cortian fibers of the ear, and the rods and cones of the eye (p. 239) serve to convert the vibrations into pulsations which act as stimuli of the appropriate nerve. The molecular change thus produced in the nerve fibers is propagated to the brain.--See _Popluar Physics_, p. 182.] carries them to the fibers of the auditory nerve, which conveys them to the brain, and gives to the mind the idea of sound.

CARE OF THE EAR.--The delicacy of the ear is such that it needs the greatest care. Cold water should not be allowed to enter the auditory canal. If the wax accumulate, never remove it with a hard instrument, lest the delicate membrane be injured, but with a little warm water, after which turn the head to let the water run out, and wipe the ear dry. The hair around the ears should never be left wet, as it may chill this sensitive organ. If an insect get in the external ear, pour in a little oil to kill it, and then remove with tepid water. The object of the Eustachian tube is to admit air into the ear, and thus equalize the pressure on the membrane. If it become closed by a cold, or if, from any cause, the pressure be made unequal, so as to produce an unpleasant feeling in the ear, relief may often be obtained by grasping the nose and forcibly swallowing. (See p. 350.)

5. SIGHT.

FIG. 61.

DESCRIPTION.--The eye is lodged in a bony cavity, protected by the overhanging brow. It is a globe, about an inch in diameter. The ball is covered by three coats--(l) the _sclerotic_, _d_, a tough, horny casing, which gives shape to the eye, the convex, transparent part in front forming a window, the _cornea_, _d_; (2) the _choroid_, _e_, a black lining, to absorb the superfluous light [Footnote: Neither white rabbits nor albinos have this black lining, and hence their sight is confused.] and (3) the _retina_, _b_, a membrane in which expand fibers of the _optic nerve_, _o_. The _crystalline lens_, _a_, brings the rays of light to a focus on the retina. The lens is kept in place by the ciliary processes, _g_, arranged like the rays in the disk of a passion flower. Between the cornea and the crystalline lens is a limpid fluid termed the _aqueous humor_; while the _vitreous humor_--a transparent, jelly-like liquid fills the space (_h_) back of the crystalline lens. The pupil, _k_, is a hole in the colored, muscular curtain, _i_, the _iris_ (rainbow). (See p. 352.)

FIG. 62.

EYELIDS AND TEARS.--The eyelids are close-fitting shutters to screen the eye. The inner side is lined with a mucous membrane that is exceedingly sensitive, and thus aids in protecting the eye from any irritating substance. The looseness of the skin favors swelling from inflammation or the effusion of blood, as in a "black eye." The eyelashes serve as a kind of sieve to exclude the dust, and, with the lids, to shield against a blinding light. Just within the lashes are oil glands, which lubricate the edges of the lids, and prevent them from adhering to each other. The tear or _lachrymal_ gland, _G_, is an oblong body lodged in the bony wall of the orbit. It empties by several ducts upon the inner surface, at the outer edge of the upper eyelid. Thence the tears, washing the eye, run into the _lachrymal lake_, _D_, a little basin with a rounded border fitted for their reception. On each side of this lake two canals, _C_, _C_, drain off the overplus through the duct, _B_, into the nose. In old age and in disease, these canals fail to conduct the tears away, and hence the lachrymal lake overflows upon the face.

FIG. 63.

STRUCTURE OF THE RETINA.--In Fig. 63 is shown a section of the retina, greatly magnified, since this membrane never exceeds 1/80 an inch in thickness. On the inner surface next to the vitreous humor, is a lining membrane not shown in the cut. Next to the choroid and comprising about 1/4 the entire thickness of the retina, is a multitude of transparent, colorless, microscopic rods, _a_, evenly arranged and packed side by side, like the seeds on the disk of a sunflower. Among them, at regular intervals, are interspersed the cones, _b_. Delicate nerve fibers pass from the ends of the rods and cones, each expanding into a granular body, _c_, thence weaving a mesh, _d_, and again expanding into the granules, _f_. Last is a layer of fine nerve fibers, _g_, and gray, ganglionic cells, _h_, like the gray matter of the brain, whence filaments extend into _i_, the fibers of the optic nerve. (See p. 354.)

The layer of rods and cones is to the eye what the bristles, otoliths, and Cortian fibers are to the ear. Indeed, the nerve itself is insensible to light. At the point where it enters the eye, there are no rods and cones, and this is called the _blind spot_. A simple experiment will illustrate the fact. Hold this book directly before the face, and, closing the left eye, look steadily with the right at the left-hand circle in Fig. 64. Move the book back and forth, and a point will be found where the right-hand circle vanishes from sight. At that moment its light falls upon the spot where the rods and cones are lacking.

FIG. 64.

HOW WE SEE.--There is believed to be a kind of universal atmosphere, termed _ether_, filling all space. This substance is infinitely more subtle than the air, and occupies its pores, as well as those of all other substances. As sound is caused by waves in the atmosphere, so light is produced by waves in the ether. A lamplight, for example, sets in motion waves of ether, which pass in through the pupil of the eye, to the retina, where the rods and cones transmit the vibration through the optic nerve to the brain, and then the mind perceives the light. (Note, p. 236.)

THE USE OF THE CRYSTALLINE LENS. [Footnote: The uses of the eye and ear are dependent upon the principles of Optics and Acoustics. They are therefore best treated in Physics.]--A convex lens, as a common burning glass, bends the rays of light which pass through it, so that they meet at a point called the _focus_. The crystalline lens converges the rays of light which enter the eye, and brings them to a focus on the retina. [Footnote: The cornea and the humors of the eye act in the same manner as the crystalline lens, but not so powerfully.] The healthy lens has a power of changing its convexity so as to adapt [Footnote: The simplest way of experimenting on the "adjustment of the eye" is to stick two stout needles upright into a straight piece of wood,--not exactly, but nearly in the same straight line, so that, on applying the eye to one end of the piece of wood, one needle (A) shall be seen about six inches off, and the other (B) just on one side of it, at twelve inches distance. If the observer looks at the needle B he will find that he sees it very distinctly, and without the least sense of effort; but the image of A is blurred, and more or less double. Now, let him try to make this blurred image of the needle A distinct. He will find he can do so readily enough, but that the act is accompanied by a sense of fatigue. And in proportion as A becomes distinct, B will become blurred. Nor will any effort enable him to see A and B distinctly at the same time.--HUXLEY.] itself to near and to distant objects. (See Fig. 66.)

FIG. 65.

NEAR AND FAR SIGHT.--If the lens be too convex, it will bring the rays to a focus before they reach the retina; if too flat, they will reach the retina before coming to a focus. In either case, the sight will be indistinct. A more common defect, however, is in the shape of the globe of the eye, which is either flattened or elongated. In the former case (see _G_, Fig. 67), objects at a distance can be seen most distinctly-- hence that is called farsightedness. [Footnote: This should not be confounded with the long sight of old people, which is caused by the stiffness of the ciliary muscles, whereby the lens can not adapt itself to the varying distances of objects.] In the latter, objects near by are clearer, and hence this is termed nearsightedness. Farsightedness is remedied by convex glasses; nearsightedness, by concave. When glasses will improve the sight they should be worn; [Footnote: Dr. Henry W. Williams, the celebrated ophthalmologist, says that, in some cases, glasses are more necessary at six or eight years of age than to the majority of healthy eyes at sixty. Sometimes children find accidentally that they can see better through grandmother's spectacles. They should then be supplied with their own.] any delay will be liable to injure the eyes, by straining their already impaired power. Cataract is a disease in which there is an opacity of the crystalline lens or its capsules, which obscures the vision. The lens may be caused to be absorbed, or may be removed by a skillful surgeon and the defect remedied by wearing convex glasses.

FIG. 66.

FIG. 67.

COLOR-BLIND PERSONS receive only two of the three elementary color sensations (green, red, violet). The spectrum appears to them to consist of two decidedly different colors, with a band of neutral tint between. The extreme red end is invisible, and a bright scarlet and a deep green appear alike. They are unable to distinguish between the leaves of a cherry tree and its fruit by the color of the two, and see no difference between blue and yellow cloth. Whittier, the poet, it is said, could not tell red from green unless in direct sunlight. Once he patched some damaged wall paper in his library by matching a green vine in the pattern with one of a bright autumnal crimson. This defect in the eye is often unnoticed, and many railway accidents have doubtless happened through an inability to detect the color of signal lights.

CARE OF THE EYES.--The shape of the eye can not be changed by rubbing and pressing it, as many suppose, but the sight may thus be fatally injured. Children troubled by nearsightedness should not lean forward at their work, as thereby the vessels of the eye become overcharged with blood. They should avoid fine print, and try, in every possible way, to spare their eyes. If middle age be reached without especial difficulty of sight, the person is comparatively safe. Most cases of squinting are caused by longsightedness, the muscles being strained in the effort to obtain distinct vision. In childhood, it may be cured by a competent surgeon, who will generally cut the muscle that draws the eye out of place.

After any severe illness, especially after measles, scarlatina, or typhoid fever, the eyes should be used with extreme caution, since they share in the general debility of the body, and recover their strength slowly. Healthy eyes even should never be used to read fine print or by a dim light. Serious injury may be caused by an imprudence of this kind. Reading upon the cars is also a fruitful source of harm. The lens, striving to adapt itself to the incessantly varying distance of the page, soon becomes wearied. Whenever the eyes begin to ache, it is a warning that they are being overtaxed and need rest.

Objects that get into the eye should be removed before they cause inflammation; rubbing in the meantime only irritates and increases the sensitiveness. If the eye be shut for a few moments, so as to let the tears accumulate, and the upper lid be then lifted by taking hold of it at the center, the cinder or dust is often washed away at once. Trifling objects can be removed by simply drawing the upper lid as far as possible over the lower one; when the lid flies back to its place, the friction will detach any light substance. If it becomes necessary, turn the upper lid over a pencil, and the intruder may then be wiped off with a handkerchief. "Eye-stones" are a popular delusion. When they seem to take out a cinder, it is only because they raise the eyelid, and allow the tears to wash it out. No one should ever use an eyewash, except by medical advice. The eye is too delicate an organ to be trifled with, and when any disease is suspected, a reliable physician should be consulted. This is especially necessary, since, when one eye is injured, the other, by sympathy, is liable to become inflamed, and perhaps be destroyed.

When reading or working, the _light should be at the left side, or at the rear; never in front_.

The constant increase of defective eyesight among the pupils in our schools is an alarming fact. Dr. Agnew considers that our schoolrooms are fast making us a spectacle-using people. Nearsightedness seems to increase from class to class, until in the upper departments, there are sometimes as high as fifty per cent of the pupils thus afflicted. The causes are (1), desks so placed as to make the light from the windows shine directly into the eyes of the scholars; (2), cross lights from opposite windows; (3), insufficient light; (4), small type that strains the eyes; and (5), the position of the pupil as he bends over his desk or slate, causing the blood to settle in his eyes. All these causes can be remedied; the position of the desks can be changed; windows can be shaded, or new ones inserted; books and newspapers that try the eyes can be rejected; and every pupil can be taught how to sit at study.

PRACTICAL QUESTIONS.

1. Why does a laundress test the temperature of her flatiron by holding it near her cheek?

2. When we are cold, why do we spread the palms of our hands before the fire?

3. What is meant by a "furred tongue"?

4. Why has sand or sulphur no taste?

5. What was the origin of the word palatable?

6. Why does a cold in the head injure the flavor of our coffee?

7. Name some so-called flavors that are really sensations of touch.

8. What is the object of the hairs in the nostrils?

9. What use does the nose subserve in the process of respiration?

10. Why do we sometimes hold the nose when we take unpleasant medicine?

11. Why was the nose placed over the mouth?

12. Describe how the hand is adapted to be the instrument of touch.

13. Besides being the organ of taste, what use does the tongue subserve?

14. Why is not the act of tasting complete until we swallow?

15. Why do all things have the same flavor when one's tongue is "furred" by fever?

16. Which sense is the more useful--hearing or sight?

17. Which coat is the white of the eye?

18. What makes the difference in the color of eyes?

19. Why do we snuff the air when we wish to obtain a distinct smell?

20. Why do red-hot iron and frozen mercury (-40°) produce the same sensation?

21. Why can an elderly person drink tea which to a child would be unbearably hot?

22. Why does an old man hold his paper so far from his eyes?

23. Would you rather be punished on the tips of your fingers than on the palm of your hand?

24. What is the object of the eyelashes? Are the hairs straight?

25. What is the use of winking?

26. When you wink, do the eyelids touch at once along their whole length? Why?

27. How many rows of hairs are there in the eyelashes?

28. Do all nations have eyes of the same shape?

29. Why does snuff taking cause a flow of tears?

30. Why does a fall cause one to "see stars"?

31. Why can we not see with the nose, or smell with the eyes?

32. What causes the roughness of a cat's tongue?

33. Is the cuticle essential to touch?

34. Can one tickle himself?

35. Why does a bitter taste often produce vomiting?

36. Is there any danger in looking "crosseyed" for fun?

37. Should schoolroom desks face a window?

38. Why do we look at a person to whom we are listening attentively?

39. Do we really feel with our fingers?

40. Is the eye a perfect sphere? (See Fig. 61.)

41. How often do we wink?

42. Why is the interior of a telescope or microscope often painted black?

43. What is "the apple of the eye"?

44. What form of glasses do old people require?

45. Should we ever wash our ears with cold water?

46. What is the object of the winding passages in the nose?

47. Can a smoker tell in the dark, whether or not his cigar is lighted?

48. Will a nerve reunite after it has been cut?

49. Will the sight give us an idea of solidity? [Footnote: A case occurred a few years ago, in London, where a friend of my own performed an operation upon a young woman who had been born blind, and, though an attempt had been made in early years to cure her, it had failed. She was able just to distinguish large objects, the general shadow, as it were, without any distinct perception of form, and to distinguish light from darkness. She could work well with her needle by the touch, and could use her scissors and bodkin and other implements by the training of her hand, so to speak, alone Well, my friend happened to see her, and he examined her eyes, and told her that he thought he could get her sight restored; at any rate, it was worth a trial. The operation succeeded; and, being a man of intelligence and quite aware of the interest of such a case, he carefully studied and observed it; and he completely confirmed all that had been previously laid down by the experience of similar cases. There was one little incident which will give you an idea of the education which is required for what you would suppose is a thing perfectly simple and obvious. She could not distinguish by sight the things that she was perfectly familiar with by the touch, at least when they were first presented to her eyes. She could not recognize even a pair of scissors. Now, you would have supposed that a pair of scissors, of all things in the world, having been continually used by her, and their form having become perfectly familiar to her hands, would have been most readily recognized by her sight; and yet she did not know what they were; she had not an idea until she was told, and then she laughed, as she said, at her own stupidity. No stupidity at all; she had never learned it, and it was one of those things which she could not know without learning. One of the earliest cases of this kind was related by the celebrated Cheselden, a surgeon of the early part of last century. Cheselden relates how a youth just in this condition had been accustomed to play with a cat and a dog; but for some time after he attained his sight he never could tell which was which, and used to be continually making mistakes. One day, being rather ashamed of himself for having called the cat the dog, he took up the cat in his arms and looked at her very attentively for some time stroking her all the while; and in this way he associated the impression derived from the touch, and made himself master (so to speak) of the whole idea of the animal. He then put the cat down, saying: "Now, puss, I shall know you another time."--CARPENTER.]

50. Why can a skillful surgeon determinate the condition of the brain and other internal organs by examining the interior of the eye? [Footnote: This is done by means of an instrument called the ophthalmoscope. Light is thrown into the eye with a concave mirror, and the interior of the organ examined with a lens.]

51. Is there any truth in the idea that the image of the murderer can be seen in the eye of the dead victim?

52. What is the length of the optic nerve? _Ans_. About three fourths of an inch.

53. Why does an injury to one eye generally affect the other eye? _Ans_. The optic nerves give off no branches in passing from their origin in two ganglia situated between the cerebrum and the cerebellum, and their termination in the eyeballs; but, in the middle of their course, they _decussate_, or unite in one mass. The fibers of the two nerves here pass from side to side, and intermingle. The two ganglia are also united directly by fibers. Thus the eyes are not really separate organs of sight, but a kind of double organ to perform, a single function.

IX.

HEALTH AND DISEASE.--DEATH AND DECAY.

"Health is the vital principle of bliss."

THOMSON.

"There are three wicks to the lamp of a man's life: brain, blood, and breath. Press the brain a little, its light goes out, followed by both the others. Stop the heart a minute, and out go all three of the wicks. Choke the air out of the lungs, and presently the fluid ceases to supply the other centers of flame, and all is soon stagnation, cold, and darkness."

O. W. HOLMES.

"Calmly he looked on either Life, and here Saw nothing to regret, or there to fear; From Nature's temp'rate feast rose satisfy'd, Thank'd Heaven that he had lived, and that he died."

POPE.

HEALTH AND DISEASE.--DEATH AND DECAY.

VALUE OF HEALTH.--The body is the instrument which the mind uses. If it be dulled or nicked, the effect of the best labor will be impaired. The grandest gifts of mind or fortune are comparatively valueless unless there be a healthy body to use and enjoy them. The beggar, sturdy and brave with his outdoor life, is really happier than the rich man in his palace with the gout to twinge him amid his pleasures. The day has gone by when delicacy is considered an element of beauty. Weakness is timid and irresolute; strength is full of force and energy. Weakness walks or creeps; strength speeds the race, wins the goal, and rejoices in the victory.

FALSE IDEAS OF DISEASE.--It was formerly supposed that diseases were caused by evil spirits, who entered the body, and deranged its action. Incantations, spells, etc., were resorted to in order to drive them out. By others, disease was thought to come arbitrarily, or as a special visitation of an overruling power. Hence, it was to be removed by fasting and prayer. Modern science teaches us that disease is not a thing, but a state. When our food is properly assimilated, the waste matter promptly excreted, and all the organs work in harmony, we are well; when any derangement of these functions occurs, we are sick. Sickness is discord, as health is concord. If we abuse or misuse any instrument, we impair its ability to produce a perfect harmony. A suffering body is simply the penalty of violated law.

PREVENTION OF DISEASE.--Doubtless a large proportion of the ills which now afflict and rob us of so much time and pleasure might easily be avoided. A proper knowledge and observance of hygienic laws would greatly lessen the number of such diseases as consumption, catarrh, gout, rheumatism, dyspepsia, etc. There are parts of England where one half the children die before they are five years old. Every physiologist knows that at least nine tenths of these lives could be saved by an observance of the simple laws of health. Professor Bennet, in a lecture at Edinburgh, estimated that one hundred thousand persons die annually in Great Britain from causes easily preventable.

With the advance of science, the causes of many diseases have been determined. Vaccination has been found to prevent or mitigate the ravages of smallpox. Scurvy, formerly so fatal among sailors that it was deemed "a mysterious infliction of Divine Justice against which man strives in vain," is now entirely avoided by the use of vegetables or lime juice. Cholera, whose approach still strikes dread, and for which there is no known specific, is but the penalty for filthy streets, bad drainage, and overcrowded tenements, and may be controlled, if not prevented, by suitable sanitary measures. It was, no doubt, the intention that we should wear out by the general decay of all the organs, [Footnote: So long as the phenomena of waste and repair are in harmony--so long, in other words, as the builder follows the scavenger--so long man exists in integrity and repair--just, indeed, as houses exist. Derange nutrition, and at once degeneration, or rather let us say, alteration begins. Alas! that we are so ignorant that there are many things about our house, which, seeing them, weaken, we know not how to strengthen. About the brick and the mortar, the frame and the rafters, we are not unlearned; but within are many complexities, many chinks and crannies, full in themselves of secondary chinks and crannies, and these so small, so deep, so recessed, that it happens every day that the destroyer settles himself in some place so obscure, that, while he kills, he laughs at defiance. You or I meet with an accident in our watch. We consult the watchmaker, and he repairs the injury. If we were all that watchmakers, like ourselves, should be, a man could be made to keep time until he died from old age or annihilating accident. This I firmly and fully believe.--_Odd Hours of a Physician_.] rather than by the giving out of any single part, and that all should work together harmoniously until the vital force is exhausted.

CURE OF DISEASE.--The first step in the cure of any disease is to obey the law of health which has been violated. If medicine be taken, it is not to destroy the disease, since that is not a thing to be destroyed, but to hold the deranged action in check while nature repairs the injury, and again brings the system into harmonious movement. This tendency of nature is our chief reliance. The best physicians are coming to have diminished confidence in medicine itself, and to place greater dependence upon sanitary and hygienic measures, and upon the efforts which nature always makes to repair injuries and soothe disordered action. They endeavor only to give to nature a fair chance, and sometimes to assist her by the intelligent employment of proper medicines. The indiscriminate use of patent nostrums and sovereign remedies of whose constituents we know nothing, and by which powerful drugs are imbibed at haphazard, can not be too greatly deprecated. When one needs medicine, he needs also a competent physician to advise its use.

DEATH AND DECAY.--By a mystery we can not understand, life is linked with death, and out of the decay of our bodies they, day by day, spring afresh. At last the vital force which has held death and decay in bondage, and compelled them to minister to our growth, and to serve the needs of our life, faints and yields the struggle. These powers which have so long time been our servants, gather about our dying couch, and their last offices usher us into the new life and the grander possibilities of the world to come. This last birth, we who see the fading, not the dawning, life, call death.

"O Father! grant Thy love divine, To make these mystic temples Thine, When wasting age and wearying strife Have sapp'd the leaning walls of life; When darkness gathers over all, And the last tottering pillars fall, Take the poor dust Thy mercy warms, And mold it into heavenly forms."

HOLMES.

HINTS ABOUT THE SICK ROOM

A SICK ROOM should be the lightest and cheeriest in the house. A small, close, dark bedroom or a recess is bad enough for one in health, but unendurable for a sick person. In a case of fever, and in many acute diseases, it should be remote from the noise of the family; but when one is recovering from an accident, and in all attacks where quiet is not needed, the patient may be where he can amuse himself by watching the movements of the household, or looking out upon the street.

_The ventilation must be thorough._ Bad air will poison both the sick and the well. A fireplace is, therefore, desirable. Windows should open easily. By carefully protecting the patient with extra blankets, the room may be frequently aired. If there be no direct draught, much may be done to change the air, by simply swinging an outer door to and fro many times.

A bare floor, with strips of carpet here and there to deaden noise, is cleanest, and keeps the air freest from dust. Cane-bottomed chairs are preferable to upholstered ones. All unnecessary furniture should be removed out of the way. A straw bed or a mattress is better than feathers. The bed hangings, lace curtains, etc., should be taken down. Creaking hinges should be oiled. Sperm candles are better than kerosene lamps.

_Never whisper in a sick room._ All necessary conversation should be carried on in the usual tone of voice. Do not call a physician unnecessarily, but if one be employed, _obey his directions implicitly_. Never give nostrums overofficious friends may suggest. Do not allow visitors to see the patient, except it be necessary. Never bustle about the room, nor go on tiptoe, but move in a quiet, ordinary way. Do not keep the bottles in the continued sight of the sick person. Never let drinking water stand in the room.

Do not raise the patient's head to drink, but have a cup with a long spout, or use a bent tube, or even a straw. Do not tempt the appetite when it craves no food. Bathe frequently, but let the physician prescribe the method. Give written directions to the watchers. Have all medicines carefully marked. Remove all soiled clothing, etc., at once from the room. Change the linen much oftener than in health. When you wish to change the sheets, and the patient is unable to rise, roll the under sheet tightly lengthwise to the middle of the bed; put on the clean sheet, with half its width folded up, closely to the other roll; lift the patient on to the newly-made part, remove the soiled sheet, and then spread oat the clean one.

DISINFECTANTS.

Remember, first, that deodorizers and disinfectants are not the same. A bad smell, for instance, may be smothered by some more powerful odor, while its cause remains uninfluenced. Bear also in mind the fact that no deodorizer and no disinfectant can take the place of perfect cleanliness and thorough ventilation. No purifyer can rival the oxygen contained in strong and continued currents of fresh, cold air, and every disinfectant finds an indispensable ally in floods of scalding water.

An excellent disinfectant may be made by dissolving in a pail of water either of the following: (1), a quarter of a pound of sulphate of zinc and two ounces of common salt for each gallon of water; (2), a pound and a half of copperas, for each gallon of water. Towels, bed linen, handkerchiefs, etc., should be soaked at least an hour, in a solution of the first kind, and then be boiled, before washing. [Footnote: It is _best_ to burn all articles which have been in contact with persons sick with contagious or infectious diseases.