CHAPTER XII.

THE USE OF THE MICROSCOPE IN THE STUDY OF PHYSIOLOGY.

[Sidenote: 1. The will of the Creator, by what obeyed? The power of a muscle? Amount of duty performed by the liver?]

1. THE LAW OF THE TISSUES.--The will of an infinite Creator is obeyed by atoms as well as by worlds. He has seen fit to commit all the functions of life to structures or tissues so small as to be invisible to the naked eye. A muscle, for example, as we have already learned, is composed of innumerable filaments, visible only by the aid of the microscope; and the power of the muscular mass is but the sum of the contractile power of the filaments which enter into its composition. Again, each cell of the liver, invisible to unassisted sight, is a secreting organ, and the liver performs as much duty as the sum of these minute organs renders possible and no more.

[Sidenote: 2. Necessity for using the microscope? The advantages gained by its use?]

2. THE NECESSITY OF THE MICROSCOPE.--If, therefore, we would know the real structure of the human body, we must make use of the microscope. We are not at liberty either to use it or not; we _must_ have recourse to it in order to obtain a real knowledge of the human body. Our eyes are constructed for the common offices of life, to provide for our wants and guard us from the ordinary sources of danger; but by arming them with _lenses_, the real structure of plants and animals is revealed to our intelligence; and enemies, otherwise invisible, that lie in wait in the air we breathe, and in our daily food and drink, to destroy life, are guarded against.

[Sidenote: 3. What are convex lenses? Kind of lenses used in microscopes? Experiment? Picture thrown upon the eye? Derivation of the word microscope?]

3. CONVEX LENSES, or magnifying glasses, are disks of glass or other transparent substance, which have the {237} property of picturing upon the retina of the eye an image of an object larger than the image produced there without their aid. The glasses used in microscopes are either double convex lenses (_a_) or plano-convex lenses (_b_). If a double convex lens or a plano-convex one be placed over a hole in the shutter of a darkened room, or over the key-hole of a door, and a piece of paper be held at a proper distance, a picture of all objects in front of the lens will be thrown on the paper, as in the camera-obscura or the magic-lantern. Now, in the same manner, a lens throws a picture of objects to which it is directed on the retina of the eye, and when that picture is larger than the image made in the eye by the object, without the aid of the lens, it is magnified, or the lens has served as a _microscope_, so called, from its use in seeing small objects, from _mikros_, small, and _skopeo_, to see.

[Sidenote: 4. Kinds of microscope? What are simple microscopes?]

4. DIFFERENT KINDS OF MICROSCOPES.--Microscopes are either _simple_ or _compound_. The glasses of magnifying spectacles, like those commonly used by aged persons, are simple microscopes. Magnifying glasses, mounted in frames such as are for sale by opticians and others, for the detection of counterfeit money, are simple microscopes, and are useful in studying the coarser structure of plants and animals.

[Sidenote: 5. Construction of the most powerful simple microscopes? In practice? A doublet? Triplet? Why are compound microscopes superior to simple ones?]

5. The most powerful simple microscopes are made by melting in a flame a thread of spun glass, so as to form a {238} minute globule or bead, which, when set in a piece of metal and used to examine objects on a plate of glass held up to the light, gives a high magnifying power. In practice, however, it is found better to use several magnifying glasses of moderate power, than a simple lens alone of high power. A combination of two lenses is called a _doublet_--of three, a _triplet_. All _simple_ microscopes throw an enlarged image of the object upon the retina. _Compound_ microscopes are so constructed that the enlarged image of an object is again magnified by a second lens, and hence their magnifying power is vastly superior to that of simple microscopes.

[Sidenote: 6. Explain, by means of the diagram, the action of the compound microscope.]

6. The accompanying diagrams will explain the action of the compound microscope compared with that of the simple microscope. In Fig. 58, which represents the working of the simple microscope, the rays from the object (_a b_), passing through the lens (L), form an image (_a' b'_) in the retina of the eye (E), and as all images are inverted in the eye, the object is seen as all other objects are, and appears erect. In Fig. 59 is seen the action of the compound microscope. An inverted image (_a' b'_) of the object (_a b_) is magnified by the second lens (L'), and an erect image is thrown upon the retina, which, as all other objects seen erect with the naked eye are inverted, gives to the image a contrary direction, or inverts it to the mind.

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[Sidenote: 7. Portions, in a compound microscope? The glasses?]

7. A COMPOUND MICROSCOPE consists of two portions: the optical portion, or the lenses, and the mechanical portion, or the instrument which bears the lenses. The glasses of a compound microscope are two: the _object-glass_ (D), Fig. 60, and the lower lens of Fig. 59, and the _ocular_ or _eye-piece_ (A), Fig. 60, and the upper piece of Fig. 59. Both the object-glass and the eye-piece may, and usually do, consist of more than one lens, for, as previously mentioned, better results are obtained by a combination of lenses of moderate power than by single lenses of high power and great curvature.

[Sidenote: 8. How to choose a microscope? How to use it?]

8. HOW TO CHOOSE AND USE A MICROSCOPE.--No attractiveness in the mechanical part of a microscope can compensate for inferior lenses; and the very first consideration in the choice of an instrument should be the excellence of the optical part of the instrument. In the use of the instrument, care should be exercised to keep the lenses clean, free from dust, not to press the object-glass upon the object under observation, and not to wet it in the water in which most objects are examined. A good microscope requires its own table; and when not in use should be covered by a bell glass or a clean linen cloth.

{240} [Illustration: FIG. 60.

A, Eye-piece. B, Body. C, Collar. D, Object-glass. E, Stage. F, Hinge. G, Mirror. H, Stand.]

[Sidenote: 9. The characteristics of the best instrument? What special requisites should be insisted upon? Why, as to a horizontal stage?]

9. The mechanical portion of the instrument varies greatly in different instruments. That one is the best which is simplest, the most solid and easily managed. The stage (E), upon which the object is placed, should not be movable: it should be solid and firm. The screw by which the focal distance is adjusted, and which {241} is in constant use, should be so placed that it can be worked by the hand resting on the table: otherwise fatigue is soon induced. The direction of the tube carrying the glasses should be perpendicular, and the stage therefore horizontal. Most objects in human anatomy are examined in water or in other liquids, or they are themselves liquids; hence an oblique stage is often inconvenient.

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[Sidenote: 10. Slides? Covers, square and circular? How kept?]

10. ADDITIONAL APPARATUS.--As almost all objects in human anatomy are examined by transmitted light thrown up from the mirror (G, Fig. 60) beneath the stage through the object to the eye, they must be placed upon strips of clear glass about three inches long and one inch wide, commonly called "slides." These should be procured with the microscope. Again, most objects seen with high powers require to be covered with a thin plate of glass, very properly called a "cover," that the moisture of the specimen may not tarnish the object-glass. Square or circular covers of very thin glass are therefore provided; and a good supply of these should be always on hand. These glasses should be kept in a covered dish filled with a mixture of alcohol and water. Simple water will not remove the fatty matter which exists in all animal tissues, and, therefore, the glasses cannot be thoroughly cleaned with it alone.

[Sidenote: 11. Cleaning the glasses? Knives, scissors, etc.? Various liquids?]

11. When glasses are required for use, they should be removed from the liquid and wiped clean and dry with a soft linen handkerchief. Delicate knives, scissors, needles mounted in handles, forceps, pipettes or little tubes for taking up water, should be obtained; these are essential to all microscopical study. The table should be supplied with glass-stoppered bottles containing the various liquids ordinarily used in the study of physiology. Thus, tincture of iodine is indispensable in studying vegetable structure, acetic acid in the study of animal tissues; and other articles will have to be added from time to time, as your progress in study demands them. {243}

[Sidenote: 12. Bodies, in air and water? The examination of starch?]

12. PRELIMINARY STUDIES.--In order to prepare the way for the study of any department of science with the aid of the microscope--for the microscope is but an eye, and can be turned in almost any direction for purposes of investigation--it is necessary to become acquainted with the many objects which are liable to complicate the examination of particular structures. Both air and water are full of floating bodies, and the most common of these should first occupy the attention. In the city, particles of starch are always floating in the air. Take a very minute portion of wheat flour, place it in the middle of a clean glass "slide," drop upon it a drop of pure water, cover it with a plate of thin glass, and examine it with a power of from one hundred to six hundred diameters. It will be found to be composed of minute grains or granules, the largest of which are made up of coats or layers, like an onion, arranged around a central spot called the _hilum_.

[Sidenote: 13. The examination with solution of iodine? Advice respecting other articles?]

13. Make another preparation in the same manner, and, after adding the water and before covering with the thin glass cover, add a small drop of a solution of iodine. Now, upon examining the specimen, every grain will be seen to be of a beautiful deep blue color. After thus studying wheat starch, the starch of Indian corn, of arrowroot, and of various grains should be examined in like manner, and their resemblances and differences noted. The granules of potato-starch are as distinctly marked as any. (See Fig. 15, page 61.)

[Sidenote: 14. Directions for examining cotton and other fibres? Vegetable hairs?]

14. Fibres of cotton, lint, and wool are liable to be found in every specimen prepared for microscopical examination. In order to study these, any cotton, woollen, or linen fabric, or garment, may be scraped, and the scrapings placed on a piece of glass moistened with water, covered with the thin glass plate or cover as before, and {244} examined with the same magnifying power, namely, from one hundred to six hundred diameters. Vegetable hairs or down are constantly floating in air and water. These are of very various forms, are simple or grouped, and form very interesting objects of study. They are readily procured from the epidermis or outer membrane of the leaves or stems of plants, by section with a delicate knife.

[Sidenote: 15. Directions for examining various tissues? Down of moths, and other structures?]

15. The tissues of plants, epidermis, ducts, and woody fibres are constantly found in microscopic preparations. They may be studied in delicate sections made with a sharp knife, or by tearing vegetable tissues apart with needles. The down of moths, the hairs of different animals, the fibres of paper, the most common animalcules in water, the dust of shelves, and generally the structures found in all vegetable and animal substances by which we are surrounded, should be studied as a preliminary to any special line of microscopical investigation.

[Sidenote: 16. Directions for examining a drop of blood?]

16. THE STUDY OF HUMAN TISSUES.--When this has been done and familiarity with the use of the instrument has been obtained, proceed to the study of the human body, for human physiology is our subject. If the end of the finger be pricked with a pin, a drop of blood may be procured for examination. Place this on one of the glass slides, cover it with a thin piece of glass, press down the cover so as to make a thin layer, and then examine with the magnifying power just mentioned. Do not add water, for that will cause the blood corpuscles to disappear. If the drop of blood is placed under the microscope at once after being drawn from the finger, most interesting phenomena will be observed. The red corpuscles will be seen to arrange themselves in rows, like piles of coin, while the blood is coagulating. The spherical, white corpuscles will {245} be left out of the rows of red disks, and, if the highest power be used, will be seen to change their shape constantly.

[Sidenote: 17. Examination of the scales of the mouth? Dandruff?]

17. If you scrape with a dull knife the inside of the cheek, the flattened scales of "pavement epithelium," or of the insensible covering which, analogous to the scarf-skin on the outer surface of the body, lines the cavities of its interior, may be readily studied. They have the appearance of transparent tiles, each enclosing a round or oval body, called its nucleus. Dandruff and the scrapings from the skin of the body are composed of scales like those of the mouth, but they differ somewhat in being hardened by horny matter, and in having a very faint central body or nucleus.

[Sidenote: 18. In what, as respects the tissues, do the warm blooded animals differ? Statement of Milne Edwards?]

18. THE TISSUES OF THE INFERIOR ANIMALS.--The warm-blooded animals do not differ in the tissues, or microscopic structures, that compose them, but only in the amount and arrangement of these tissues. Milne Edwards says these tissues "do not differ much in different animals, but their mode of association varies; and it is chiefly by reason of the differences in the combination of these associations in various degrees, that each species possesses the anatomical properties and characters which are peculiar to it."

[Sidenote: 19. How to procure materials for the study of the tissues of man?]

19. Hence the butcher's stall will furnish all the materials for the study of the microscopic tissues. The structure of the heart, lungs, liver, brain, and muscle may all be studied, and well studied, by using minute pieces of the flesh of the lower animals, especially of the quadrupeds. Such portions of these animals as are not exposed for sale can be readily obtained by order from the slaughter-house. To examine with the powers of which we have been speaking, it is only necessary to cut off {246} exceedingly small pieces, tear them apart with needles, or make very delicate sections with a sharp knife.

20. INCENTIVES TO STUDY.--A complete knowledge of all minute structures is not to be expected at once, for you are here introduced into a new realm of Nature, a world of little things as vast, as wonderful, and as carefully constructed as the starry firmament,--that other realm of grand objects which the astronomer nightly scans with the telescope. It will not appear singular, therefore, if, at first, you feel strange and awkward in this new creation. With a little perseverance, however, and with the attention directed toward simple objects at the outset, it will not be long before an increasing experience will engender confidence.

21. If to all this there be added an enthusiastic study of the standard authorities on the subject, the rate of progress will be by so much the more rapid. As compared with similar studies, few possess more interest than microscopy, and to the one who pursues it with fondness, it constantly affords sources of pleasure and agreeable surprises; and in the end, often leads to new and valuable additions to the sum of human knowledge. The depths which the microscope is employed to fathom are no more completely known, than are the heights above us explored and comprehended by the astronomer.

QUESTIONS FOR TOPICAL REVIEW.

_State what you can on the following subjects_:

1. Voice and speech 227, 228 2. The organ of the voice 228, 229 3. The vocal cords 230, 231 4. The production of the voice 232, 233 5. The varieties of voice 233, 234 6. Ventriloquism 235 7. The law of the tissues 236 8. Necessity of the microscope 236 9. Convex lenses 236, 237 10. Kinds of microscope 237, 238 11. Choosing a microscope 239, 242 12. Preliminary studies 243, 244 13. The study of human tissues 244 14. The study of the inferior animals 245

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APPENDIX.

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POISONS AND THEIR ANTIDOTES.

Accidents from poisoning are of such frequent occurrence, that every one should be able to administer the more common antidotes, until the _services of a physician can be obtained_. As many poisons bear a close resemblance to articles in common use, no dangerous substance should be brought into the household without having the word _poison_ plainly written or printed on the label; and any package, box, or vial, without a label, should be at once destroyed, if the contents are not positively known.

When a healthy person is taken severely and _suddenly_ ill _soon after some substance has been swallowed_, we may suspect that he has been poisoned. In all cases where poison has been taken into the stomach, it should be quickly and thoroughly evacuated by some active emetic, which can be speedily obtained. This may be accomplished by drinking a tumblerful of warm water, containing either a tablespoonful of powdered mustard or of common salt, or two teaspoonfuls of powdered alum in two tablespoonfuls of syrup. When vomiting has already taken place, it should be maintained by copious draughts of warm water or mucilaginous drinks, such as gum-water or flaxseed tea, and tickling the throat with the finger until there is reason to believe that all the poisonous substance has been expelled from the stomach.

The following list embraces only the more common poisons, together with such antidotes as are usually at hand, to be used until the physician arrives.

POISONS.

ACIDS.--_Hydrochloric acid_; _muriatic acid_ (spirits of salt); _nitric acid_ (aqua fortis); _sulphuric acid_ (oil of vitriol).

ANTIDOTE.--An antidote should be given at once to neutralize the acid. Strong soapsuds is an efficient remedy, and can always be obtained. It should be followed by copious draughts of warm water or flaxseed tea. Chalk, magnesia, soda or saleratus (with water) or {248} lime-water, are the best remedies. When sulphuric acid has been taken, water should be given sparingly, because, when water unites with this acid, intense heat is produced.

_Oxalic acid._

ANTIDOTE.--Oxalic acid resembles Epsom salts in appearance, and may easily be mistaken for it. The antidotes are magnesia, or chalk mixed with water.

PRUSSIC ACID; _oil of bitter almonds_; _laurel water_; _cyanide of potassium_ (used in electrotyping).

ANTIDOTE.--Cold douche to the spine. Chlorine water, or water of ammonia largely diluted, should be given, and the vapor arising from them may be inhaled.

ALKALIES AND THEIR SALTS.--AMMONIA (hartshorn), _liquor or water of ammonia_. POTASSA:--_caustic potash_, _strong ley_, _carbonate of potassa_ (pearlash), _nitrate of potassa_ (saltpetre).

ANTIDOTE.--Give the vegetable acids diluted, as weak vinegar, acetic, citric, or tartaric acids dissolved in water. Castor oil, linseed oil, and sweet oil may also be used; they form soaps when mixed with the free alkalies, which they thus render harmless. The poisonous effects of saltpetre must be counteracted by taking mucilaginous drinks freely, so as to produce vomiting.

ALCOHOL.--_Brandy_, _wine_; _all spirituous liquors_.

ANTIDOTE.--Give as an emetic ground mustard or tartar emetic. If the patient cannot swallow, introduce a stomach pump; pour cold water on the head.

GASES.--_Chlorine_, _carbonic acid gas_, _carbonic oxide_, _fumes of burning charcoal_, _sulphuretted hydrogen_, _illuminating or coal-gas_.

ANTIDOTE.--For poisoning by chlorine, inhale, cautiously, ammonia (hartshorn). For the other gases, cold water should be poured upon the head, and stimulants cautiously administered; artificial respiration. (See _Marshall Hall's Ready Method_, page 250.)

METALS.--_Antimony_, _tartar emetic_, _wine of antimony_, etc.

ANTIDOTE.--If vomiting has not occurred, it should be produced by tickling the throat with the finger or a feather, and the abundant use of warm water. Astringent infusions, such as common tea, oak bark, and solution of tannin, act as antidotes.

ARSENIC.--_White arsenic_, _Fowler's solution_, _fly-powder_, _cobalt_, _Paris green_, etc.

ANTIDOTE.--Produce vomiting at once with a tablespoonful or two of powdered mustard in a glass of warm water, or with ipecac. The antidote is hydrated peroxide of iron. If Fowler's solution has been taken, lime-water must be given. {249}

COPPER.--_Acetate of copper_ (verdigris), _sulphate of copper_ (blue vitriol), food cooked in dirty _copper vessels_, or pickles made green by _copper_.

ANTIDOTE.--Milk or white of eggs, with mucilaginous drinks (flaxseed tea, etc.), should be freely given.

IRON.--_Sulphate of iron_ (copperas), etc.

ANTIDOTE.--Carbonate of soda in some mucilaginous drink, or in water, is an excellent antidote.

LEAD.--_Acetate of lead_ (sugar of lead), _carbonate of lead_ (white lead), water kept in _leaden pipes_ or _vessels_, food cooked in _vessels_ glazed with _lead_.

ANTIDOTE.--Induce vomiting with ground mustard or common salt in warm water. The antidote for soluble preparations of lead is Epsom salts; for the insoluble forms, sulphuric acid largely diluted.

MERCURY.--_Bichloride of mercury_ (corrosive sublimate), _ammoniated mercury_ (white precipitate), _red oxide of mercury_ (red precipitate), _red sulphuret of mercury_ (vermilion).

ANTIDOTE.--The white of eggs, or wheat flour beaten up with water and milk, are the best antidotes.

SILVER.--_Nitrate of silver_ (lunar caustic).

ANTIDOTE.--Give a teaspoonful of common salt in a tumbler of water. It decomposes the salts of silver and destroys their activity.

ZINC.--_Sulphate of zinc_, etc. (white vitriol).

ANTIDOTE.--The vomiting may be relieved by copious draughts of warm water. The antidote is carbonate of soda administered in water.

NARCOTIC POISONS.--_Opium_ (laudanum, paregoric, salts of morphia, Godfrey's cordial, Dalby's carminative, soothing syrup, cholera mixtures), _aconite_, _belladonna_, _hemlock_, _stramonium_, _digitalis_, _tobacco_, _hyosciamus_, _nux vomica_, _strychnine_.

ANTIDOTE.--Evacuate the stomach by the most active emetics, as mustard, alum, or sulphate of zinc. The patient should be kept in motion, and cold water dashed on the head and shoulders. Strong coffee must be given. The physician will use the stomach pump and electricity. In poisoning by nux vomica or strychnine, etc., chloroform or ether should be inhaled to quiet the spasms.

IRRITANT VEGETABLE POISONS.--_Croton oil_, _oil of savine_, _poke_, _oil of tansy_, etc.

ANTIDOTE.--If vomiting has taken place, it may be rendered easier by copious draughts of warm water. But if symptoms of insensibility have come on without vomiting, it ought to be immediately excited by ground mustard mixed with warm water, or some other active emetic {250} and after its operation an active purgative should be given. After evacuating as much of the poison as possible, strong coffee or vinegar and water may be given with advantage.

POISONOUS FISH.--_Conger eel_, _mussels_, _crabs_, etc.

ANTIDOTE.--Evacuate, as soon as possible, the contents of the stomach and bowels by emetics (ground mustard mixed with warm water or powdered alum), and castor oil, drinking freely at the same time of vinegar and water. Ether, with a few drops of laudanum mixed with sugar and water, may afterward be taken freely.

POISONOUS SERPENTS.--ANTIDOTE.--A ligature or handkerchief should be applied moderately tight above the bite, and a cupping-glass over the wound. The patient should drink freely of alcoholic stimulants containing a small quantity of ammonia. The physician may inject ammonia into the veins.

POISONOUS INSECTS.--_Stings of scorpion_, _hornet_, _wasp_, _bee_, etc.

ANTIDOTE.--A piece of rag moistened with a solution of carbolic acid may be kept on the affected part until the pain is relieved; and a few drops of carbolic acid may be given frequently in a little water. The sting may be removed by making strong pressure around it with the barrel of a small watch-key.

DROWNING.

MARSHALL HALL'S "READY METHOD" of treatment in asphyxia from drowning, chloroform, coal gas, etc.

1st. Treat the patient _instantly on the spot_, in the _open air_, freely exposing the face, neck, and chest to the breeze, except in severe weather.

2d. In order _to clear the throat_, place the patient gently on the face, with one wrist under the forehead, that all fluid, and the tongue itself, may fall forward, and leave the entrance into the windpipe free.

3d. _To excite respiration_, turn the patient slightly on his side, and apply some irritating or stimulating agent to the nostrils, as _veratrine_, _dilute ammonia_, etc.

4th. Make the face warm by brisk friction; then dash cold water upon it.

5th. If not successful, lose no time; but, _to imitate respiration_, place the patient on his face, and turn the body gently, but completely _on the side, and a little beyond_; then again on the face, and so on, alternately. Repeat these movements, deliberately and perseveringly, {251} _fifteen times only_ in a minute. (When the patient lies on the thorax, this cavity is _compressed_ by the weight of the body, and _ex_piration takes place. When he is turned on the side, this pressure is removed, and _in_spiration occurs.)

6th. When the prone position is resumed, make a uniform and efficient pressure _along the spine_, removing the pressure immediately, before rotation on the side. (The pressure augments the _ex_piration: the rotation commences _in_spiration.) Continue these measures.

7th. Rub the limbs _upward_, with _firm pressure_ and with _energy_. (The object being to aid the return of venous blood to the heart.)

8th. Substitute for the patient's wet clothing, if possible, such other covering as can be instantly procured, each bystander supplying a coat or cloak, etc. Meantime, and from time to time, _to excite inspiration_, let the surface of the body be _slapped_ briskly with the hand.

9th. Rub the body briskly till it is dry and warm, then dash _cold_ water upon it, and repeat the rubbing.

Avoid the immediate removal of the patient, as it involves a _dangerous loss of time_--also, the use of bellows, or any _forcing_ instrument; also, the _warm bath_, and _all rough treatment_.

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GLOSSARY.

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AB-DO´MEN (Latin _abdo_, to conceal). The largest cavity of the body containing the liver, stomach, intestines, etc.; the belly.

AB-SOR´BENTS (L. _ab_ and _sorbeo_, to suck up). The vessels which take part in the process of absorption.

AB-SORP´TION. The process of sucking up fluids by means of an animal membrane.

AC-COM-MO-DA´TION of the Eye. The alteration in the shape of the crystalline lens, which accommodates or adjusts the eye for near and remote vision.

AC´ID, LACTIC (L. _lac_, milk). The acid ingredient of sour milk; the gastric juice also contains it.

AL-BU´MEN, or Albumin (L. _albus_, white). An animal substance resembling white of egg.

AL-BU´MI-NOSE (from _albumen_). A soluble animal substance produced in the stomach by the digestion of the albuminoid substances.

AL-BU´MIN-OID substances. A class of proximate principles resembling albumen; they may be derived from either the animal or vegetable kingdoms.

AL´I-MENT (L. _alo_, to nourish). That which affords nourishment; food.

AL-I-MENT´A-RY CA-NAL (from _aliment_). A long tube in which the food is digested, or prepared for reception into the system.

AN-ÆS-THET´ICS (Greek, [Greek: an], _an_, without, [Greek: aisthesia], _aisthesia_, feeling).--Those medicinal agents which prevent the feeling of pain, such as chloroform, laughing-gas, etc.

AN-I-MAL´CULE (L. _animal´culum_, a small animal). Applied to animals which can only be seen with the aid of the microscope. Animalculum (plural, animalcula) is used with the same meaning.

A-OR´TA (Gr. [Greek: aorteomai], _aorteomai_, to be lifted up). The largest artery of the body, and main trunk of all the arteries. It arises from the left ventricle of the heart. The name was first applied to the two large branches of the trachea, which appear to be lifted up by the heart.

{253} A´QUE-OUS HUMOR (L. _aqua_, water). A few drops of watery colorless fluid occupying the space between the cornea and crystalline lens.

A-RACH´NOID MEM´BRANE (Gr. [Greek: arachne], _arachne_, a cobweb, and [Greek: eidos], _eidos_, like). An extremely thin covering of the brain and spinal cord. It lies between the _dura mater_ and the _pia mater_.

AR´BOR VI´TÆ (L.). Literally, "the tree of life;" a name given to the peculiar appearance presented by a section of the cerebellum.

AR´TER-Y (Gr. [Greek: aer], _aer_, air, and [Greek: terein], _terein_, to contain). A vessel by which blood is conveyed away from the heart. It was supposed by the ancients to contain air; hence the name.

AR-TIC-U-LA´TION (L. _articulo_, to form a joint). The more or less movable union of bones, etc.; a joint.

A-RYT´E-NOID CAR´TI-LA-GES (Gr. [Greek: arutaina], _arutaina_, a pitcher). Two small cartilages of the larynx, resembling the mouth of a pitcher.

AS-SIM-I-LA´TION (L. _ad_, to, and _similis_, like). The conversion of food into living tissue.

AU-DI´TION (L. _audio_, to hear). The act of hearing sounds.

AU´DI-TO-RY NERVE. One of the cranial nerves; it is the special nerve of hearing.

AU´RI-CLE (L. _auris_, the ear). A cavity of the heart.

BAR´I-TONE (Gr. [Greek: barus], _barus_, heavy, and [Greek: tonos], _tonos_, tone). A variety of male voice between the bass and tenor.

BEL-LA-DON´NA (It. beautiful lady). A vegetable narcotic poison. It has the property of enlarging the pupil, and thus increasing the brilliancy of the eye; so called from its use by Italian ladies.

BI-CUS´PID (L. _bi_, two, and _cuspis_, prominence). The name of the fourth and fifth teeth on each side of the jaw; possessing two prominences.

BILE. The gall, or peculiar secretion of the liver; a viscid, yellowish fluid, and very bitter to the taste.

BRONCH´I (Gr. [Greek: bronkos], _bronkos_, the windpipe). The two first divisions or branches of the trachea; one enters each lung.

BRONCH´I-AL TUBES. The smaller branches of the trachea within the substance of the lungs, terminating in the air-cells.

BRONCH-I´TIS (from _bronchia_, and _itis_, a suffix signifying inflammation). An inflammation of the larger bronchial tubes; a "cold" affecting the lungs.

CAL-CA´RE-OUS (L. _calx_, lime). Containing lime.

CA-NAL´ (L.). In the body, any tube or passage.

CA-NINE´ (L. _canis_, a dog). Name given to the third tooth on each {254} side of the jaw; in the upper jaw it is also known as the eye-tooth: pointed like the tusks of a dog.

CAP´IL-LA-RY (L. _capil´lus_, a hair, _capilla´ris_ hair-like). The name of the extremely minute blood-vessels which connect the arteries with the veins.

CAR´BON DIOX-IDE (CO_{2}). Chemical name for carbonic acid gas.

CAR-BON´IC A-CID. The gas which is present in the air expired from the lungs; a waste product of the animal kingdom, and a food of the vegetable kingdom.

CAR´DI-AC (Gr. [Greek: kardia], _cardia_, the heart). The cardiac orifice of the stomach is the upper one, and is near the heart; hence its name.

CAR-NIV´O-ROUS (L. _ca´ro_, flesh, and _vo´ro_, to devour). Subsisting upon flesh.

CA-ROT´ID AR-TE-RY. The large artery of the neck, supplying the head and brain.

CAR´TI-LAGE. A solid but flexible material, forming a part of the joints, air-passages, nostrils, etc.; gristle.

CA´SE-INE (L. _ca´seus_, cheese). The albuminoid substance of milk; it forms the basis of cheese.

CER-E-BEL´LUM (diminutive for _cer´ebrum_, the brain). The little brain, situated beneath the posterior third of the cerebrum.

CER´E-BRUM (L.). The brain proper, occupying the entire upper portion of the skull. It is nearly divided into two equal parts, called "hemispheres," by a cleft extending from before backward.

CHO´ROID (Gr. [Greek: chorion], _chorion_, a membrane or covering). The middle tunic or coat of the eyeball.

CHYLE (Gr. [Greek: chulos], chulos, juice). The milk-like fluid formed by the digestion of fatty articles of food in the intestines.

CHYME (Gr. [Greek: chumos], _chumos_, juice). The pulpy liquid formed by digestion within the stomach.

CIL´I-A (pl. of _cil´i-um_, an eyelash). Minute, vibratile, hair-like processes found upon the cells of the air-passages, and other parts that are habitually moist.

CIR-CU-LA´TION (L. _cir´culus_, a ring). The circuit, or course of the blood through the blood-vessels of the body, from the heart to the arteries, through the capillaries into the veins, and from the veins back to the heart.

CO-AG-U-LA´TION (L. _coag´ulo_, to curdle). Applied to the process by which the blood clots or solidifies.

COCH´LE-A (L. _coch´lea_, a snail-shell). The spiral cavity of the internal ear.

{255} CONCH´A (Gr. [Greek: konchê], _konche_, a mussel-shell). The external shell-shaped portion of the external ear.

CON-JUNC-TI´VA (L. _con_ and _jun´go_, to join together). A thin layer of mucous membrane which lines the eyelids and covers the front of the eyeball; thus joining the latter to the lids.

CON-TRAC-TIL´I-TY (L. _con_ and _tra´ho_, to draw together). The property of a muscle which enables it to contract, or draw its extremities closer together.

CON-VO-LU´TIONS (L. _con_ and _vol´vo_, to roll together). The tortuous foldings of the external surface of the brain.

CON-VUL´SION (L. _convel´lo_, to pull together). A more or less violent agitation of the limbs or body.

COR´NE-A (L. _cor´nu_, a horn). The transparent, horn-like substance which covers the anterior fifth of the eyeball.

COR´PUS-CLES, BLOOD (L. dim. of _cor´pus_, a body). The small biconcave disks which give to the blood its red color; the _white_ corpuscles are globular and larger.

COS-MET´IC (Gr. [Greek: kosmeô], _kosmeo_, to adorn). Beautifying; applied to articles which are supposed to increase the beauty of the skin, etc.

CRA´NI-AL (L. _cra´nium_, the skull). Pertaining to the skull. The nerves which arise from the brain are called cranial nerves.

CRI´COID (Gr. [Greek: krikos], _kri´kos_, a ring). A cartilage of the larynx, resembling a seal-ring in shape.

CRYS´TAL-LINE LENS (L. _crystal´lum_, a crystal). One of the so-called humors of the eye; a double convex body situated in the front part of the eyeball.

CU´TI-CLE (L. dim. of _cu´tis_, the skin). The scarf-skin; also called the _epider´mis_.

CU´TIS (Gr. [Greek: skutos], _skutos_, a skin or hide). The true skin, lying beneath the cuticle; also called the _der´ma_.

DE-CUS-SA´TION (L. _decus´sis_, the Roman numeral ten, X). A reciprocal crossing of fibres from side to side.

DI´A-PHRAGM (Gr. [Greek: diaphrassô], _diaphrasso_, to divide by a partition). A large, thin muscle which separates the cavity of the chest from the abdomen; a muscle of respiration.

DIF-FUS´ION OF GASES. The power of gases to become intimately mingled, without reference to the force of gravity.

DUCT (L. _du´co_, to lead). A narrow tube; the _thoracic duct_ is the main trunk of the absorbent vessels.

DU-O-DE´NUM (L. _duode´ni_, twelve). The first division of the small intestines, about twelve fingers-breadth long.

{256} DU´RA MA´TER (L.). Literally, the hard mother; the tough membrane which envelops the brain.

DYS-PEP´SI-A (Gr. [Greek: dus], _dus_, difficult, and [Greek: peptô], _pep´to_, to digest). Difficult or painful digestion; a disordered condition of the stomach.

E-MUL´SION (L. _emul´geo_, to milk). Oil in a finely divided state suspended in water.

EN-AM´EL (Fr. _email_). The dense material which covers the crown of the tooth.

EN´ER-GY, Specific, of a Nerve. When a nerve of special sense is excited, whatever be the cause, the sensation experienced is that peculiar to the nerve; this is said to be the law of the specific energy of the nerves.

EP-I-GLOT´TIS (Gr. [Greek: epi], _epi_, upon, and [Greek: glôttis], _glottis_, the entrance to the windpipe). A leaf-shaped piece of cartilage which covers the top of the larynx during the act of swallowing.

EX-CRE´TION (L. _excer´no_, to separate). The separation from the blood of the waste particles of the body; also the materials excreted.

EX-PI-RA´TION (L. _expi´ro_, to breathe out). The act of forcing air out of the lungs.

EX-TEN´SION (L. _ex_, out, and _ten´do_, to stretch). The act of restoring a limb, etc., to its natural position after it has been flexed, or bent; the opposite of _Flexion_.

FE-NES´TRA (L.). Literally, a window; the opening between the middle and internal ear.

FI´BRIN (L. _fi´bra_, a fibre). An albuminoid substance found in the blood; in coagulating it assumes a fibrous form.

FLEX´ION (L. _flec´to_, to bend). The act of bending a limb, etc.

FOL´LI-CLE (L. dim. of _fol´lis_, a bag). A little pouch or depression in a membrane; it has generally a secretory function.

FUN´GOUS GROWTHS (L. _fun´gus_, a mushroom). A low grade of vegetable life.

GAN´GLI-ON (Gr. [Greek: ganglion], _ganglion_, a knot). A knot-like swelling in the course of a nerve; a smaller nerve-centre.

GAS´TRIC (Gr. [Greek: gastêr], _gaster_, stomach). Pertaining to the stomach.

GLAND (L. _glans_, an acorn). An organ consisting of follicles and ducts, with numerous blood-vessels interwoven; it separates some particular fluid from the blood.

GLOS´SO-PHAR-YN-GE´AL NERVE (Gr. [Greek: glôssa], _glossa_, the tongue, and [Greek: pharunx], _pharunx_, the throat). The nerve of taste supplying the posterior third of the tongue; it also supplies the throat.

GLU´TEN (L.). Literally, glue: the glutinous albuminoid ingredient of wheat.

{257} GRAN´ULE (L. dim. of _gra´num_, a grain). A little grain; a microscopic object.

GUS-TA´TION (L. _gus´to_, to taste) The sense of taste.

GUS´TA-TO-RY NERVE. The nerve of taste supplying the front part of the tongue; a branch of the "fifth" pair.

HÆM´OR-RHAGE (Gr. [Greek: haima], _hai´ma_, blood, and [Greek: rhêgnumi], _regnumi_, to burst). Bleeding, or the loss of blood.

HEM-I-PLE´GIA (Gr. [Greek: hêmisus], _hemisus_, half, and [Greek: plêssô], _plesso_, to strike). Paralysis, or loss of power, affecting one side of the body.

HEM´I-SPHERES (Gr. [Greek: sphaira], _sphaira_, a sphere). Half a sphere, the lateral halves of the cerebrum, or brain proper.

HE-PAT´IC (Gr. [Greek: hêpar], _hepar_, the liver). Pertaining to the liver.

HER-BIV´O-ROUS (L. _her´ba_, an herb, and _vo´ro_ to devour). Applied to animals that subsist upon vegetable food.

HU´MOR (L.). Moisture: the humors are transparent contents of the eyeball.

HY-DRO-PHO´BI-A (Gr. [Greek: hudor], _hudor_, water, and [Greek: phobeô], _phobeo_, to fear). A disease caused by the bite of a rabid dog or other animal. In a person affected with it, convulsions are occasioned by the sight of a glittering object, like water, by the sound of running water, and by almost any external impression.

HY´GI-ENE (Gr. [Greek: hugieia], _huygieia_, health). The art of preserving health and preventing disease.

HY´PER-O-PI-A. Abbreviated from HY´PER-MET-RO´PI-A (Gr. [Greek: huper], _huper_, beyond, [Greek: metron], _metron_, the measure, and [Greek: ôps], _ops_, the eye). A defect of vision dependent upon a too short eyeball; so called because the rays of light are brought to a focus at a point behind the retina; the true "far sight."

IN-CI´SOR (L. _inci´do_, to cut). Applied to the four front teeth of both jaws, which have sharp cutting edges.

IN´CUS (L). An anvil; the name of one of the bones of the middle ear.

IN-SAL-I-VA´TION (L. _in_, and _sali´va_, the fluid of the mouth). The mingling of the saliva with the food during the act of chewing.

IN-SPI-RA´TION (L. _in_, and _spi´ro_, _spira´tum_, to breathe). The act of drawing in the breath.

IN-TEG´U-MENT (L. _in_, and _te´go_, to cover). The skin, or outer covering of the body.

IN-TES´TINE (L. _in´tus_, within). The part of the alimentary canal which is continuous with the lower end of the stomach; also called the intestines, or the bowels.

I´RIS (L. _i´ris_, the rainbow). The thin muscular ring which lies {258} between the cornea and crystalline lens, and which gives the eye its brown, blue, or other color.

JU´GU-LAR (L. _ju´gulum_, the throat). The name of the large veins which run along the front of the neck.

LAB´Y-RINTH (Gr. [Greek: laburinthos], _laburin´thos_, a building with many winding passages). The very tortuous cavity of the inner ear, comprising the vestibule, semicircular canals, and the cochlea.

LACH´RY-MAL APPARATUS (L. _lach´ryma_, a tear). The organs for forming and conveying away the _tears_.

LAC´TE-ALS (L. _lac_, _lac´tis_, milk). The absorbent vessels of the small intestines; during digestion they are filled with chyle, which has a milky appearance.

LA-RYN´GO-SCOPE (Gr. [Greek: larunx], _larunx_, the larynx, and [Greek: skopeô], _skopeo_, to look at). The instrument by which the larynx may be examined in the living subject.

LAR´YNX (Gr.). The cartilaginous tube situated at the top of the windpipe, or trachea; the organ of the voice.

LENS (L.). Literally, a lentil; a piece of transparent glass or other substance so shaped as either to converge or disperse the rays of light.

LIG´A-MENT (L. _li´go_, to bind). A strong, fibrous material binding bones or other solid parts together; it is especially necessary to give strength to joints.

LIG´A-TURE. A thread of silk or other material used in tying around an artery.

LYMPH (L. _lym´pha_, spring-water). The colorless, watery fluid conveyed by the lymphatic vessels.

LYM-PHAT´IC VESSELS. A system of absorbent vessels.

MAL´LE-US (L.). Literally, the mallet; one of the small bones of the middle ear.

MAR´ROW. The soft, fatty substance contained in the central cavities of the bones: the spinal marrow, however, is composed of nervous tissue.

MAS-TI-CA´TION (L. _mas´tico_, to chew). The act of cutting and grinding the food to pieces by means of the teeth.

ME-DUL´LA OB-LON-GA´TA. The "oblong marrow," or nervous cord, which is continuous with the spinal cord within the skull.

MEM-BRA´NA TYM´PAN-I (L.). Literally, the membrane of the drum; a delicate partition separating the outer from the middle ear; it is sometimes incorrectly called the drum of the ear.

MEM´BRANE. A thin layer of tissue serving to cover some part of the body.

MI´CRO-SCOPE (Gr. [Greek: mikros], _mikros_, small, and [Greek: skopeô], _skopeo_, to {259} look at). An optical instrument which assists in the examination of minute objects.

MO´LAR (L. _mo´la_, a mill). The name applied to the three back teeth of each side of the jaw; the grinders, or mill-like teeth.

MO´TOR (L. _mo´veo_, _mo´tum_, to move). Causing motion; the name of those nerves which conduct to the muscles the stimulus which causes them to contract.

MU´COUS MEMBRANE. The thin layer of tissue which covers those internal cavities or passages which communicate with the external air.

MU´CUS. The glairy fluid which is secreted by mucous membranes, and which serves to keep them in a moist condition.

MY-O´PI-A (Gr. [Greek: muô], _muo_, to contract, and [Greek: ôps], _ops_, the eye). A defect of vision dependent upon an eyeball that is too long, rendering distant objects indistinct; near-sight.

NA´SAL (L. _na´sus_, the nose). Pertaining to the nose; the _nasal cavities_ contain the distribution of the special nerve of smell.

NERVE (Gr. [Greek: neuron], _neuron_, a cord or string). A glistening, white cord of cylindrical shape, connecting the brain or spinal cord with some other organ of the body.

NERVE CELL. A minute, round and ashen-gray cell found in the brain and other nervous centres.

NERVE FI´BRE. An exceedingly slender thread of nervous tissue found in the various nervous organs, but especially in the nerves; it is of a white color.

NU-TRI´TION (L. _nu´trio_, to nourish). The processes by which the nourishment of the body is accomplished.

OE-SOPH´A-GUS (Gr.). Literally, that which carries food. The tube leading from the throat to the stomach; the gullet.

O-LE-AG´I-NOUS (L. _o´leum_, oil). Of the nature of oil: applied to an important group of food-principles--the fats.

OL-FAC´TO-RY (L. _olfa´cio_, to smell). Pertaining to the sense of smell.

OPH-THAL´MO-SCOPE (Gr. [Greek: ophthalmos], _ophthalmos_, the eye, and [Greek: skopeô], _skopeo_, to look at). An instrument devised for examining the interior of the globe of the eye.

OP´TIC (Gr. [Greek: optô], _opto_, to see). Pertaining to the sense of sight.

OR´BIT (L. _or´bis_, the socket). The bony socket or cavity in which the eyeball is situated.

OS´MOSE (Gr. [Greek: ôsmos], _osmos_, a thrusting or impulsion). The process by which liquids are impelled through a moist membrane.

OS´SE-OUS (L. _os_, a bone). Consisting of, or resembling bone.

PAL´ATE (L. _pala´tum_, the palate). The roof of the mouth, consisting of the hard and soft palate.

{260} PAL´MAR. Relating to the palm of the hand.

PAN´CRE-AS (Gr. [Greek: pas], [Greek: pantos], _pas_, _pantos_, all, and [Greek: kreas], _kreas_, flesh). A long, flat gland situated near the stomach; in the lower animals the analogous organ is called the sweet-bread.

PA-PIL´LÆ (L. _papil´la_). The minute prominences in which terminate the ultimate fibres of the nerves of touch and taste.

PA-RAL´Y-SIS. A disease of the nervous system marked by the loss of sensation, or voluntary motion, or both; palsy.

PAR-A-PLE´GI-A (Gr. [Greek: paraplêssô], _paraplesso_, to strike amiss). A form of paralysis affecting the lower half of the body.

PA-TEL´LA (L. dim. of _pat´ina_, a pan). The knee-pan; a small bone.

PEL´VIS (L.). Literally a basin; the bony cavity at the lower part of the trunk.

PEP´SIN (Gr. [Greek: peptô], _pepto_, to digest). The organic principle of the gastric juice.

PER-I-STAL´TIC MOVE´MENTS (Gr. [Greek: peristellô], _peristello_, to contract). The slow, wave-like movements of the stomach and intestines.

PER-I-TO-NE´UM (Gr. [Greek: periteinô], _periteino_, to stretch around). The investing membrane of the stomach, intestines, and other abdominal organs.

PER-SPI-RA´TION (L. _perspi´ro_, to breathe through). The sweat, or watery exhalation of the skin; when visible, it is called _sensible_ perspiration, when invisible, it is called _insensible_ perspiration.

PE´TROUS (Gr. [Greek: petra], _petra_, a rock). The name of the hard portion of the temporal bone, in which is situated the drum of the ear and labyrinth.

PHAR´YNX (Gr. [Greek: pharunx], _pharunx_, the throat). The cavity between the back of the mouth and gullet.

PHYS-I-OL´O-GY (Gr. [Greek: phusis], _phusis_, nature, and [Greek: logos], _logos_, a discourse). The science of the functions of living, organized beings.

PI´A MA´TER (L.). Literally, the tender mother; the innermost of the three coverings of the brain. It is thin and delicate; hence the name.

PLEU´RA (Gr. [Greek: pleura], a rib). A membrane covering the lung and lining the chest. There is one for each lung.

PLEU´RI-SY. An inflammation affecting the pleura.

PNEU-MO-GAS´TRIC (Gr. [Greek: pneumôn], _pneumon_, the lungs, and [Greek: gastêr], _gaster_, the stomach). The name of a nerve distributed to the lungs and stomach; it is the principal nerve of respiration.

PNEU-MO´NIA (Gr.). An inflammation affecting the air-cells of the lungs.

{261} PRES-BY-O´PI-A (Gr. [Greek: presbus], _presbus_, old, and [Greek: ôps], _ops_, the eye). A defect of the accommodation of the eye, caused by the hardening of the crystalline lens; the "far-sight" of adults and aged persons.

PROC´ESS (L. _proce´do_, _proces´sus_, to proceed, to go forth). Any projection from a surface. Also, a method of performance; a procedure.

PTY´A-LIN (Gr. [Greek: ptualon], _ptualon_, saliva). The peculiar organic ingredient of the saliva.

PUL´MO-NA-RY (L. _pul´mo_, _pulmo´nis_, the lungs). Pertaining to the lungs.

PULSE (L. _pel´lo_, _pul´sum_, to beat). The striking of an artery against the finger, occasioned by the contraction of the heart, commonly felt at the wrist.

PU´PIL (L. _pupil´la_). The central, round opening in the iris, through which light passes into the depths of the eye.

PY-LO´RUS (Gr. [Greek: pulôros], _puloros_, a gate-keeper). The lower opening of the stomach, at the beginning of the small intestine.

RE´FLEX ACTION. An involuntary action of the nervous system, by which an external impression conducted by a sensory nerve is reflected, or converted into a motor impulse.

RES-PI-RA´TION (L. _res´piro_, to breathe frequently). The function of breathing, comprising two acts: _inspiration_, or breathing in, and _expiration_, or breathing out.

RET´I-NA (L. _re´te_, a net). The innermost of the three tunics or coats of the eyeball, being an expansion of the optic nerve.

SAC´CHA-RINE (L. _sac´charum_, sugar). Of the nature of sugar; applied to the important group of food substances which embraces the different varieties of sugar, starch, and gum.

SA-LI´VA (L.). The moisture or fluids of the mouth, secreted by the salivary glands, etc.

SCLE-ROT´IC (Gr. [Greek: sklêros], _skleros_, hard). The tough, fibrous outer tunic of the eyeball.

SE-BA´CEOUS (L. _sebum_, fat). Resembling fat, the name of the oily secretion by which the skin is kept flexible and soft.

SE-CRE´TION (L. _secer´no_, _secre´tum_, to separate). The process of separating from the blood some essential important fluid; which fluid is also called a secretion.

SEM-I-CIR´CU-LAR CANALS. A portion of the internal ear.

SEN-SA´TION. The perception of an external impression by the nervous system; a function of the brain.

SEN-SI-BIL´I-TY, GENERAL. The power possessed by nearly all parts {262} of the human body of recognizing the presence of foreign objects that come in contact with them.

SE´RUM (L.). The watery constituent of the blood, which separates from the clot during the process of coagulation.

SKEL´E-TON (Gr.). The bony framework of an animal, the different parts of which are maintained in their proper relative positions.

SPEC´TRO-SCOPE (from _spec´trum_ and [Greek: skopeô], _scopeo_, to examine the spectrum). An instrument employed in the examination of the spectrum of the sun or any other luminous body.

SPHYG´MO-GRAPH (Gr. [Greek: sphugmos], _sphugmos_, the pulse, and [Greek: graphô], _grapho_, to write). An ingenious instrument by means of which the pulse is delineated upon paper.

STA´PES (L.). Literally, a stirrup; one of the small bones of the tympanum, or middle ear, resembling somewhat a stirrup in shape.

SYM-PA-THET´IC SYSTEM OF NERVES. A double chain of nervous ganglia, connected together by numerous small nerves, situated chiefly in front of and on each side of the spinal column.

SYN-O´VI-A (Gr. [Greek: sun], _sun_, and [Greek: ôon], _oon_, resembling an egg). The lubricating fluid of joints, so called because it resembles the white of egg.

SYS´TO-LE (Gr. [Greek: sustellô], _sustello_, to contract). The contraction of the heart, by which the blood is expelled from that organ.

TAC´TILE (L. _tac´tus_, touch). Relating to the sense of touch.

TEM´PO-RAL (L. _tem´pus_, time, and _tem´pora_, the temples). Pertaining to the temples; the name of an artery: so called, because the hair begins to turn white with age in that portion of the scalp.

TEN´DON (L. _ten´do_, to stretch). The white, fibrous cord or band by which a muscle is attached to a bone; a sinew.

TET´A-NUS (Gr. [Greek: teinô], _teino_, to stretch). A disease marked by persistent contractions of all or some of the voluntary muscles; those of the jaw are sometimes solely affected: the disorder is then termed locked-jaw.

THO´RAX (Gr. [Greek: thôrax], _thorax_, a breastplate). The upper cavity of the trunk of the body, containing the lungs, heart, etc.; the chest.

THY´ROID (Gr. [Greek: thureos], _thureos_, a shield). The largest of the cartilages of the larynx; its angular projection in the front of the neck is called "Adam's apple."

TRA´CHE-A (Gr. [Greek: trachus], _trachus_, rough). The windpipe, or the largest of the air-passages; composed in part of cartilaginous rings, which render its surface rough and uneven.

TRANS-FU´SION (L. _transfun´do_, to pour from one vessel to another). {263} The operation of injecting blood taken from one person into the veins of another; other fluids than blood are sometimes used.

TRICH-I´NA SPI-RA´LIS. (L.) A minute species of parasite or worm, which infests the flesh of the hog, and which may be introduced into the human system by eating pork not thoroughly cooked.

TYM´PA-NUM (Gr. [Greek: tumpanon], _tumpanon_, a drum). The cavity of the middle ear, resembling a drum in being closed by two membranes, and in having communication with the atmosphere.

U´VU-LA (L. _uva_, a grape). The small pendulous body attached to the back part of the palate.

VAS´CU-LAR (L. _vas´culum_, a little vessel). Pertaining to, or containing blood-vessels.

VE´NOUS (L. _ve´na_, a vein). Pertaining to, or contained within a vein.

VEN-TI-LA´TION. The introduction of fresh air into a room or building, in such a manner as to keep the air within it in a pure condition.

VEN-TRIL´O-QUISM (L. _ven´ter_, the belly, and _lo´quor_, to speak). A modification of natural speech by which the voice is made to appear to come from a distance. The ancients supposed that the voice was formed in the belly; hence the name.

VEN´TRI-CLES of the heart. The two largest cavities of the heart, situated at its apex or point.

VER´TE-BRAL COLUMN (L. _ver´tebra_, a joint). The back-bone, consisting of twenty-four separate bones, called vertebræ, firmly jointed together; also called the spinal column and spine.

VES´TI-BULE. A portion of the internal ear, communicating with the semicircular canals and the cochlea; so called from its fancied resemblance to the vestibule or porch of a house.

VIL´LI (L. _vil´lus_, the nap of cloth). Minute thread-like projections found upon the internal surface of the small intestine, giving it a velvety appearance.

VIT´RE-OUS (L. _vi´trum_, glass). Having the appearance of glass; applied to the humor occupying the largest part of the cavity of the eyeball.

VIV-I-SEC´TION (L. _vi´vus_, alive, and _se´co_, to cut). The practice of operating upon living animals, for the purpose of studying some physiological process.

VOCAL CORDS. Two elastic bands or ridges situated in the larynx; they are the essential parts of the organs of the voice.

* * * * *

{265}

INDEX.

o------

A. PAGE Absorbent vessels, 97 Absorption, 96 by blood-vessels, 96 by the lacteals, 96 of the food, 96 Accommodation, function of, 213 Achilles, tendon of, 27 Adam's apple, 229 Air, atmospheric, 131 Changes in, in respiration, 132 Carbonic acid in, 138 Composition of, 131 Dust in the, 137 Effects of impure, 139 Impurities in, 136 Matters in the expired, 132 Provision for purifying, 141 Renovation by ventilation, 142 Air-cells of the lungs, 125 Air-passages, 125 Albinos, 44 Albumen, 58 of the blood, 102 Albuminoid substance, 57 Varieties of, 57 Properties of, 57-58 Albuminose, 94 Alcoholic liquors, 77 Physiological action of, 78 Alimentary canal, 81 Animal functions, 143 Animal heat, 143 how produced, 143 regulated by perspiration, 145 Animals, relative strength of, 28 Apoplexy, 171 Aqueous humor, 210 Arachnoid membrane, 152 Arbor vitæ, 154 Arterial blood, 107-135 differs from venous, 135 Arteries, 114 Arrangement of, 115 Carotid, 116 Distribution of, 115 Pulsation of, 115 Radial, 116 Temporal, 116 Arytenoid cartilage, 229 Asphyxia, 250 Assimilation, 80, 121 Audition, 215 Auditory canal, 218 nerve, 222 Auricles of the heart, 109

B.

Back-bone, 21 Bathing, 47 Importance of, 47 Time and manner of, 49 Baths, 48 Different kinds of, 48 Belladonna, 206 dilates the pupil, 206 Use as a cosmetic, 206 Bile, 95 Secretion of, in the liver, 95 Accumulation of, in the gall-bladder, 95 Uses of, 95 Biliary duct, 95 Bladder, Gall-, 95 Bleeding, how stopped, 121 Blind-spot, 207 Blood, 101 Arterial, 107-135 Change of color, 107 Circulation of, 107, 133 Coagulation of, 105 Composition of, 102 corpuscles, 102, 103 fluid, 105 Microscopic appearance of, 102 Respiratory changes in, 133 Uses of the, 105 Venous, 107, 135 Blood-vessels, 114, 118 Absorption by, 96 Injuries to the, 121 Body, renovation of the, 66 Bones, 15 Form and composition of, 16 Growth of, 22 Microscopic structure of, 17 Repair of, 23 Structure of, 17 Uses of, 15 Bowels, 94 Brain, 150 Anatomical structure of, 152 Function of the, 172 Injuries of the, 173 Membranes of the, 152 Reflex action of the, 174 {266} Bread, 72 Bronchial tubes, 125 Bronchitis, 128

C.

Canals, Semicircular, 223 Capillary blood-vessels, 118 Circulation in the, 118 Carbonic acid, 132 exhaled from the lungs, 132 in the air, 138 retention in the blood, 134 Cartilage, 20 Arytenoid, 229 Cricoid, 229 Thyroid, 229 Casein, 58 Cataract, 210 Cells, Nerve, 150, 159 Ciliated, 128 Cerebellum, 153 Function of the, 172 Cerebro-spinal nervous system, 150 Cerebrum, 152 Function of the, 172 Cheese, 58 Chest, Framework of, 19 Contents of the, 19 Chocolate, 77 Chorea, 169 Choroid coat of the eye, 204 Chyle, 95 Chyme, 94 Cilia, 128 Circulation, 107 in the frog's foot, 119 of the blood, 107 Rapidity of, 120 through the heart, 112 through the lungs, 123 Clothing, 51 Coagulation of milk, 58 of the blood, 104 Cochlea, 223 Coffee, 75 Effects of, 75, 76 Collar-bone, 19 Color-blindness, 209 Column, Spinal, 21 Combustion, Spontaneous, 145 Complexion, 44 Concha of the ear, 217 Conjunctiva, 200 Contraction of heart, 111 of muscles, 27 Convulsions, 169 Cooking, 70 Cords, Vocal, 126, 230 Cornea, 203 Corpuscles, Blood, 102 Cosmetics, 51 Cranial ganglia, 150 Functions of, 171 Cranial nerves, 154 Cranium, 19 Cricoid cartilage, 229 Crystalline lens, 209 Uses of, 210 Cuticle, 41 Function of, 183 Cutis, 42

D.

Decussation of motor and sensory fibres of spinal cord, 164 Dentition of infancy, 82 Diaphragm, Movements of the, in respiration, 128, 129 Diastole of the heart, 111 Diet, Mixed, 66, 85 Necessity for changing, 67 Necessity of a regulated, 62 The best, 63 Digestion, 80 Circumstances affecting, 97 Gastric, 93 Intestinal, 94 Nature of, 81 Organs of, 81-91 Drowning, 250 Duct, Biliary, 95 Nasal, 201 Pancreatic, 95 Thoracic, 97 Dura Mater, 152

E.

Ear, 217 External, 217 Internal, 222 Middle, 219 Foreign bodies in, 225 Drum of the, 219 Bones of the, 220 Ear-sand, 223 Ear-stones, 223 Ear-wax, 219 Eggs, 68 Composition of, 68 Emulsion of fats, in digestion, 95 Enamel of the teeth, 82 Epiglottis, 126, 229 Uses of, 126, 220 Eustachian tube, 221 Exercise, 30 Different modes of, 31 Effects of, 30 Importance of, 30 Open-air, 33 Expiration, 128 Movements of, 129 Extensor muscles, 26 Eye, 198 Eyeball, 203 Eyelashes, 200 Eyelids, 200

F.

Fats, 59 Emulsion of, 59 Source of, in food, 59 Fenestra ovalis, 224 Fibres, Muscular, 25 {267} Fibres, Nervous, 149 Fibrine in food, 58 of the blood, 102 Fish, as food, 71 Flexor muscles, 26 Food, 53 Animal, 67 Daily quantity of, 65 Ingredients of, 54-62 Necessity for, 64 Source of, 53 Vegetable, 71

G.

Gall-bladder, 95 Ganglia, cranial, Functions of the, 171 Gases, Interchange of, in the lungs, 134 Gastric digestion, 93 Gastric juice, 91 Action of, 93 Daily quantity of, 92 General sensibility, 179 Glands, Perspiratory, 45 Salivary, 86 Sebaceous, 44 Glossary, 252 Glosso-pharyngeal nerve, 189 Gullet, 90 Gum, 61 as food, 62 Gustatory nerve, 189 Gymnastics, 33-38 for schools and colleges, 33

H.

Hair, 42 Uses of, 44 Hearing, Sense of, 215 Protection of, 224 Heart, 107 Cavities of the, 109, 110 Circulation through the, 112 Frequency of action, 112 Movements of the, 111 Valves of the, 112 Heat, Animal, 143 Production of, 143 Regulation of, 145 Hemiplegia, 165 Humor, Aqueous, 210 Crystalline, 209 Vitreous, 210 Hunger, 65 Seat of the sensation of, 65 Hydra, 149 Hydrophobia, 169 Hygiene, 13 Hyperopia, 212

I.

Incus, 220 Inorganic substances in food, 54 Insalivation, 86, 88 Insensible perspiration, 46 Inspiration, 128 Intestinal juice, 95 Action of, 96 Intestines, 94 Complete digestion in the small, 94 Villi of the, 96 Iris, 205 Function of, 205 Iron, 56 Proportion in the blood, 57 Proportion in the food, 57

J.

Joints, 19 Varieties of, 20 Juice, gastric, 91 Intestinal, 95 Pancreatic, 95

L.

Labyrinth, 222 Lachrymal canals, 201 gland, 201 Lacteals, 96 Absorption by, 96 Lactic acid in gastric juice, 92 Lactometer, 68 Large intestines, 94 Laryngoscope, 231 Larynx, 125, 228 Production of the voice in the, 126, 228 Lens, crystalline, 209 Ligaments, 19 Light, theory of, 197 Lime in the bones, 16 in the food, 56 Importance of, 56 Liver, 95 Secretion of the, 95 Locked jaw, 169 Long-sight, 212 Lungs, 123 Capacity of, 130 Structure of, 125 Lymph, 97 Lymphatic vessels, 97

M.

Magendie, on pain, 181 Magnesia, Compounds of, in food, 57 Malleus, 220 Marrow of the bones, 17 Mastication, 82 Importance of, 88, 89 Meats, 68 The cooking of, 69 The preservation of, 69 Membrane of the tympanum, 219 Medulla oblongata, 154 Function of the, 171 Microscope, 236 The value of the, 236 Simple, 237 Compound, 239 The use of the, 239 {268} Milk, 68 Composition of, 68 Specific gravity of, 68 Milk-teeth, 82 Mucous membrane of air passages, 127 Muscles, 25 Function of the, 25 Flexion and extension of, 26 Voluntary and involuntary, 26 Muscular contraction, 27 fibres, 25 sense, 188 Myopia 212

N.

Nails, 42 Uses of the, 44 Nasal cavities, 192 duct, 201 Nerve, Auditory, 222 Glossopharyngeal, 189 Gustatory, 189 Olfactory, 193 Optic, 197 Sympathetic, 158 Nerve cells, 150, 159 Nerve fibres, 149 Nerves, Cranial, 154 Spinal, 156 Functions of the, 160 Sensory, functions of the, 160 Motor, functions of the, 160 Sympathetic system of, 158 Nervous system, 148, 149 Cerebro-spinal, 150 Nervous tissue, Properties of, 159 Nose, 192 Nutrition, Processes of, 80

O.

Oesophagus, 90 Oil, Sources of, in food, 59 Old-sight, 215 Olfactory nerve, 193 Optic nerve, 197 Orbicular bone, 220 Orbit of the eye, 199 Organic substances as food, 57-62 Organs of circulation, 107 Digestion, 81-91 Respiration, 123 Sight, 198 Voice, 228 Oxygen, 131 Amount of, consumed in respiration, 132 Continually supplied to the atmosphere, 141

P.

Pain, Relations of, to pleasure, 181 Sensation of, 180 Uses of, 180 Pancreatic juice, 95 Uses of, 95 Pancreatin, 95 Paraplegia, 163 Parlor gymnasium, 36 Passages, Air, 125 Pelvis, 19 Pepsin, 92 Peristaltic action of the stomach, 92 Peritoneum, 94 Perspiration, Daily amount of, 46 Sensible and insensible, 46 Uses of, 46, 145 Perspiratory glands, 45 Physical strength, 29 Culture, 33 Physiology, 11 Animal, 11 Comparative, 11 Human, 11 Vegetable, 11 Pia mater, 152 Plasma of the blood, 102 Pleura, 124 Pleurisy, 128 Pneumo gastric nerve, 171 Pneumonia, 128 Poisons and their antidotes, 247 Potash in the blood, 57 Potato, 73 Presbyopia, 215 Preservation of the teeth, 85 Ptyalin, 88 Pulsation of the heart, 113 of the arteries, 116 Pulse, 115 Form of the, 116 Writer, 116 Pylorus, 90

R.

Radial artery, 116 Red corpuscles of the blood, 102 Reflex action of the spinal cord, 165 Requisites for, 167 Uses of, 167, 170 Causing convulsions, 169 Objects of, 170 of the brain, 174, 175 Rennet, 58 Respiration, 123 Change of blood in, 123-133 Frequency of, 129 Movements of, 128 Object of, 123 Organs of, 123 Respiratory labor, 135 Rest, necessity for, 38 Retina, 206 Retinal light, 207 Ribs, Movements of, in respiration, 128

S.

Saccharine substances, 60 Saliva, 86 Importance of, 88 Secretion of, 86 Salivary glands, 86, 87 {269} Salt, Common, 55 Importance of, 56 Sclerotic coat of the eyeball, 204 Sebaceous glands, 44 Secretion of, 45 Semicircular canals, 223 Sensation of pain, 180 Relations of, to pleasure, 181 of temperature, 187 of weight, 188 Modification of, 178 Production of, 177 Variety of, 178 Sense of hearing, 215 sight, 196 smell, 192 taste, 189 touch, 184 Sense, muscular, 188 thermal, 187 Senses, Special, 177 Sensibility, General, 179 Short-sight, 212 Sinews, 27 Sight, Sense of, 196 Organs of, 198 Skeleton, 19 Skin, 41 Structure of, 41 Skull, 19 Uses of the, 19 Sleep, Necessity for, 38 Amount required, 39 Small intestines, 94 Smell, Sense of, 192 Nerve of, 193 Uses of, 194 Soda in the food, 57 Sound, Production of, 215 Special senses, 177 Spectroscope, 104 Speech, 227 Relation of, to the sense of hearing, 228 Sphygmograph, 116 Spinal column, 21 Spinal cord, 155 Decussation of the, 164 Direction of fibres in, 164 Functions of the, 162 Nerves of, 156 Reflex action of, 165 Spontaneous combustion, 145 Stapes, 220 Starch, 61 Its change into sugar, 61 Different kinds, 61 Effect of boiling, 61 Microscopic appearance, 61 Stimulating substances, 62 Stomach, 90, 92 Digestion, 93 Movements of, 92 Secretion of, 92 St. Vitus' dance, 169 Sugar, 60 Varieties, 60 Sources of, 61 Sun-bath, 50 Sympathetic system of nerves, 158 Synovia, 20 Systole of the heart, 111

T.

Taste, Association of, 190 Education of, 191 Organ of, 188 Sense of, 189 Tea, Effect of, 76 Kinds of, 76 Tears, 201 Escape of the, 201 Teeth, 82 Temporary set of, 82 Permanent set of, 83 Bicuspid, 83 Canine, 83 Incisor, 83 Molar, 84 Arrangement of, 85 of different animals, 85 Preservation of, 85 Temperature of the body, 146 Extremes of, 146 Sensations of, 187 Tendon of Achilles, 27 Tendons, 27 Tetanus, 169 Thermal, 50 Thermæ sense, 187 Thirst, 65 Thoracic duct, 97 Thorax, 19 Thyroid cartilage, 229 Tissues, intimate structure of the, 236 Human, 244 of the lower animals, 245 Tongue, 188 Nerves of, 189 Sensibility, 189 Touch, Delicacy of, 186 Organs of, 183 Sense of, 184 Trachea, 125 Transfusion, 106 Trichina spiralis, 71 Trunk, 19 Tympanum of the ear, 219 Membrane of, 219

V.

Valves of the heart, 112 of the veins, 117 Vapor, Animal, in breath, 132 Vegetable food, 71 Vegetative functions, 148 Veins, 117 Valves of, 117 Venous blood, 135 Changes of, in respiration, 133 Ventilation, 142 Ventricles of the larynx, 229 of the heart, 110 Ventriloquism, 235 {270} Vertebrae, 21 Vestibule of the internal ear, 223 Villi of the intestines, 96 Absorption by, 96 Vital knot, 171 Vitreous humor, 210 Vocal cords, 126, 230 Observation of, with laryngoscope, 231 Voice, 227 Organ of, 228 Production of, 232 Varieties of, 233

W.

Water, 74 Action of, on lead, 75 Chemically pure, 74 Croton, 74 exhaled with the breath, 132 from springs and wells, 74 Proportion of, in the blood 55 " of, in the tissues and fluids of the body, 54 Ridgewood, 74 Walking, as a means of exercise, 31 White corpuscles of the blood, 104 Wisdom teeth, 84

* * * * *

Changes made to printed original

Page 45, Sect. 12. "(4, Fig. 14)": '(4, Fig. 13)' in original.

Page 20, Sect. 20, note. "philosophy": 'philosphy' in original.

Page 101, heading. "Sphygmograph": 'Spygmograph' in original. So also in Table of Contents, but cf. p. 116 and Index.

Page 144, Sect. 46, note. "zoologists": 'zooligsts' in original.

Page 199, Sect. 53. "considerable": 'considera-ale' (on line break) in original.

Page 255, s.v. Convolutions. "external": 'extenal' in original.