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4. The functions of absorption and circulation, which are carried on, as you have learned, by the heart, stomach, lungs, etc., exist also in all vegetables. The plant imbibes the air, draws it in by means of its leaves, and after the part has been taken that is good for its nourishment, it sends it out again. If we had powers no higher than plants, we should be as they are, mechanical beings only.
5. But we have something within us—a mind or a soul—that impels all our actions. As I have stated, whenever we wish to do anything, our mind speaks, as it were, and tells the muscle to perform the act. Our bones and muscles are like the machinery of a steamboat or railroad-car; they are always ready to serve us; but as the machinery of a boat will not move without steam, so the bones and muscles, which are mere instruments of motion, will not move, when we wish to do anything, without the aid of the mind.
6. Listen, and I will tell you how the mind acts. You will remember that I informed you that the bones of the head, or the skull, served as a protection to the brain.
7. This brain is the seat of the mind or soul, and perceives all the impressions that are made on various parts of the body. If the brain be injured, the body suffers. There have been many cases in which the skull was broken, and the brain disturbed; and in every
4. What functions have vegetables in common with human beings ? How are these functions performed? What should we be if we had no higher powers than plants? 5. What impels our actions ? What do our bones and muscles resemble in a steamboat? What is necessary in the boat beside machinery? What is necessary to produce motion beside bones and muscles? What are the bones and muscles? 6. What is the brain? What does it perceive ?
IMPORTANCE OF TEE BLAN.
instance, the effects were much more serious than the most severe accidents would have been to szy ober part of the body.
8. Dr. Hayward relates the story of a bezzar in Paris, who lost a part of his skal by an accident ; the brain was slightly covered by its membranes, and he was accustomed to allow any one who woud give him a small sum of money to press on this esposed part. When the pressure was made, he was a ways unconscious of what was going on around him, or where he was; but as soon as the pressure was removed, his consciousness was restored.
9. You have probably heard of persons who had been stunned or made insensible for some time, from having received severe blows or accidents. People frequently remain in this state for a length of time, but finally recover.
10. That the brain is of great importance to us, is evident from the fact, that though it is a small part of the body, yet it receives about a fifth part of all the blood, which passes into it by means of four large arteries. It is also covered by a very hard substance, called the skull, which renders it less liable to be injured by blows. The brain has a grayish color; it is not hard like bone, but is sometimes so soft that when it is taken in the hands it will run over the sides of them.
7. What relation is there between the brain and body? How do accidents on the brain compare with those on other parts of the body? 8. Relate the story of the beggar in Paris. What was the effect of pressure on the brain ? What took place when the pressure was removed ? 9. What is said of persons who have been stunned by receiving accidents ? 10. From what do we infer the importance of the brain ? How does the blood pass into the brain? What are some of the properties of tho brain ?
11. This cut represents the top or upper surface of the brain, showing its various folds or convolutions, each of which is supposed to perform different functions.
You see by the cut that it has an irregular and wrinkled appearance, and appears just like a handkerchief when folded up, or like a piece of sponge, or scorched leather. The brain occupies considerable space when we take it in our hands, but is harder or more condensed, when it is inclosed by the bones.
11 What does the cut represent? What is the office of each fold of the brain? What is the appearance of the brain ? What does it resom. ble? When does the brain occupy the most space ?
12. The color and appearance of the human brain are very similar to those in animals ; yet it is considerably larger in proportion to the size of the body than that of almost any other animal. The human brain is four
(FF represents the cerebellum; AA represents the anterior lobe, or portion in which the intellectual faculties are situated; DD represents the middle lobe, containing the animal propensities; BB represents the posterior lobe, containing the domestic propensities.) times as large as that of an ox; yet the body of the ox is five or six times as large as the human body.
12. In what respects is the brain of man similar to that of animals ? Is the size of the brain always in proportion to the size of the body? How do they compare in the ox and man?
13. There are two great divisions of the brain, which are the cerebrum and the cerebellum. The large brain, or the cerebrum is the upper and front part; the smaller, or the cerebellum, occupies the back and lower part of the skull. These are again divided from the front to the back of the head into two parts—the right and left, called hemispheres. The brain has three coverings or membranes under the skull, which assist in protecting it.
14. There are a great many little prominences or clefts in the brain. It was in one of these projections, at the base of the brain, that Descartes, a great philosopher, supposed the soul to be situated ; but most people at the present day think that the soul or mind is connected with the whole brain.
15. The spinal marrow is contained in the spine. It is a long white cord extending from the brain, and is covered by a firm and strong membrane of bone. It is well for us that it is thus guarded from injury; for our lives and happiness depend very much on its safety. If this be injured or broken, all the members below the injured or broken part become insensible and useless.
16. A great quantity of small white cords, called nerves, proceed from the lower part of the brain, just below the cerebellum and spinal marrow, as you will perceive by the following cut.
13. What are the great divisions of the brain? Which is the cerebrum ? Which is the cerebellum ? What other divisions are there in the brain? Explain the cut. 14. Is the surface of the brain smooth and uniform ? Where did a certain philosopher suppose the soul to be situated? Where do most people at the present day place the soul or mind? 15. What does the spine contain ? Describe the spinal marrow. Why is it necessary that the brain should be well guarded ? 16. What are the nerves, and from what do they proceed ?