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