Part 57

THE SPECIAL SENSES.

229, 230. What is a sense? Name the five senses. To what organ do all the senses minister? If the nerve leading to any organ of sense be cut, what would be the effect? [Footnote: Each, organ is adapted to receive a peculiar kind of impression. Hence we can not smell with, the eyes nor see with the nose. Thus, if the nerve communicating between the brain and any organ be destroyed, that means of knowledge is cut off.] Sometimes persons lose feeling in a limb, but retain motion; why is this? What is the sense of touch sometimes called? Describe the organ of touch. What are the papillæ? Where are they most abundant? [Footnote: If we apply the points of a compass blunted with cork to different parts of the body, we can distinguish the two points at one twenty-fourth of an inch apart on the tongue, one sixteenth, of an inch on the lips, one twelfth of an inch on the tips of the fingers, and one half inch on the great toe; while, if they are one inch on the cheek, and two inches on the back, they will scarcely produce a separate sensation.--HUXLEY.] What are the uses of this sense? What special knowledge do we obtain by it? Why do we always desire to handle any curious object? Can the sense of touch always be relied upon? Illustrate. What is the tactus eruditus? Tell how one sense can take the place of another. Give illustrations of the delicacy of touch possessed by the blind.

230-232. Describe the sense of taste. How can you see the papillæ of taste? What causes the velvety look of the tongue? Why do salt and bitter flavors induce vomiting? Why does an acid "pucker" the face? What substances are tasteless? Illustrate. Has sulphur any taste? Chalk? Sand? What is the use of this sense? Does it not also add to the pleasures of life? Why are the acts of eating, drinking, etc., thus made sources of happiness?

232, 233. Describe the organ of smell. State the intimate relation which exists between the senses of smell and taste. Name some common mistakes which occur in consequence. Must the object to be smelled touch the nose? What is the theory of smell? How do you account for the statement made in the note concerning musk and ambergris? What are the uses of this sense? Are agreeable odors healthful, and disagreeable ones unhealthful?

234-236. Describe the organ of hearing. Describe the external ear. What is the tympanum or drum of the ear? Describe the middle ear. Name the bones of the ear. Describe their structure. Describe the internal ear. By what other name is it known? What substances float in the liquid which fills the labyrinth? What is their use? Describe the fibers of Corti. What do they form? Use of this microscopic harp? Give the theory of sound. Where is the sound, in the external object or in the mind? Can there be any sound, then, where there is no mind? What advice is given concerning the care of the ear? How can insects be removed? Which sense would you rather lose, hearing or sight? Does not a blind person always excite more sympathy than a deaf one? How does the sight assist the hearing? [Footnote: In hearing, the attention is more or less characteristic. If we wish to distinguish a distant noise, or perceive a sound, the head inclines and turns in such a manner as to present the external ear in the direction of the sound, at the same time the eyes are fixed and partially closed. The movement of the lips of his interlocutor is the usual means by which the deaf man supplies the want of hearing; the eyes and the entire head, from its position, having a peculiar and painful expression of attention. In looking at the portrait of La Condamine, it was easily recognized as that of a deaf person. Even when hearing is perfect, the eyes act sometimes as auxiliaries to it. In order to understand an orator perfectly, it seems necessary to see him--the gestures and the expression of the face seeming to add to the clearness of the words. The lesson of a teacher can not be well understood if any obstacle is interposed between him and the eyes of the listening pupil. So that if a pupil's eyes wander, we know that he is not attentive.-- Wonders of the Human Body.]

236, 237. Describe the eye. Name the three coats of which it is composed. Is it a perfect sphere? Ans. The cornea projects in front, and the optic nerve at the back sticks out like a handle, while the ball itself has its longest diameter from side to side. How is the interior divided? Object of the crystalline lens? How is the crystalline lens kept in place? Describe the liquids which fill the eye.

238. What is the pupil? Describe the eyelids. Why is the inner side of the eyelid so sensitive? What is the cause of a black eye? Use of the eyelashes? Where are the oil glands located? What is their use? Describe the lachrymal gland. The lachrymal lake. What causes the overflow in old age?

239. Explain the structure of the retina. Use of the rods and cones. What is the blind spot?

240. Illustrate. What is the theory of sight? Illustrate.

241, 242. State the action of the crystalline lens. Its power of adaptation. Do children ever need spectacles?

243. What is the cataract? How cured? What is color blindness? Illustrate. What care should be taken of the eyes? Should one constantly lean forward over his book or work? What special care should nearsighted children take? By what carelessness may we impair our sight?

244. How is squinting caused? Cured? What care should be used after an illness? Should we ever read or write at twilight? Danger of reading upon the ears? What course should we take when objects get into the eye? How may they be removed?

245. Are "eyestones" useful? Why should we never use eyewashes except upon the advice of a competent physician? What rule should be observed with regard to the direction of the light when we are at work? Name some causes of near-sightedness. Remedies.

346. Give the account of Laura Bridgman.

347-350. Describe the anatomy of the nose. In what part of the nose is the function of smell performed? Why do we "sniff" when our attention is attracted by an odor? Give some experiments which illustrate the connection between smell, taste, and touch. Why should we retain our food in the mouth as long as possible? Of what use are gastronomic odors?

350. Why should a child's ear never be boxed? Illustrate. How can we detect inattention from deafness in a child? What should we consider in this respect?

351. Why should we avoid direct draughts in the ear? Explain the use of earwax. What common habit is very injurious? Why?

352, 353. What is the office of the Eustachian tube? Illustrate.

353, 354. Describe the action of the "eye curtain." Give experiments. What are "Purkinje's Figures"? Describe experiment.

HEALTH AND DISEASE.

251-254. State some of the benefits of health. Contrast it with sickness. How were diseases formerly supposed to be caused? What remedies were used? What does modern science teach us to be the nature of disease? Give some illustrations showing how diseases may be prevented. Is it probable that the body was intended to give out in any one of its organs? What is the first step to be taken in the cure of a disease? What should be the object of medicine? What is now the chief dependence of the best physicians? What do you think concerning the common use of patent nostrums? Ought we not to use the greatest care in the selection of our physician?

GLOSSARY.

Ab do' men (abdo, I conceal). The largest cavity in the body, in which are hidden the intestines, stomach, etc.

Ab sorb' ent (ab, from sorbeo, I suck up).

Ac' e tab' u lum (acetum, vinegar). The socket for holding the head of the thigh bone, shaped like an ancient vinegar vessel.

A ce' tic (acetum, vinegar).

Ad' i pose. Fatty.

Al bu' men (albus, white). A substance resembling the white of egg.