Appetite, natural, 163.
Aqueous humor, 377.
Arachnoid, 299.
Arteries, 47.
Bronchial, 84.
Functions of, 51.
Pulmonary, 84.
Renal, 202.
To illustrate elasticity of, 62.
Why elastic, 48.
Articulations, 230-232.
Kinds of, 230.
Assimilation, 18, 182.
Astigmatism, 384.
Atlas, 223.
Atoms, defined, 105.
Attraction sphere, 15.
Auditory canal, 358.
Auricles, 42.
Axis, 223.
Axis cylinder, 284.
Axon, 283.
Form and length of, 284.
Function of, 306.
Structure of, 284.
Bacteria, 394.
Ball-and-socket joint, 231.
Basement membrane, 197.
Basilar membrane, 363.
Bathing, 272, 274.
Biceps muscle, action of, 263.
Bicuspids, 143.
Bile, 154, 155.
Binocular vision, 381.
Blind spot, 377.
To prove presence of, 390.
Blood, 24-39.
Changes in, 34.
Checking flow from wounds, 58.
Coagulation of, 31.
Experiments with, 37-39.
Flow of, how regulated, 50.
Functions of, 33.
Hygiene of, 34-36.
Physical properties of, 24.
Quantity of, 33.
Supply to lungs, 82.
Velocity of, 54.
Where found, 24.
Blood platelets, 25.
Blood pressure, 52, 70.
Blood pressure and velocity, 52.
Blood vessels, to strengthen, 57.
Body, organization of, 19.
Bone groups, 223-229.
Bones, 216-242.
Adaptation of, 228.
Composition, 217.
Gross structure of, 218.
Minute structure of, 219.
Observation on gross structure, 241.
Properties of, 217.
Table of, 229.
To show composition of, 241.
To show minute structure of, 242.
Bowels, rules for care of, 166.
Brachial plexus, 302.
Brain, 280, 288-291.
Disturbed circulation, 327.
Protection of, 299.
Brain workers, 408.
Breathing, _see_ Respiration.
Causes of shallow, 92.
Illustrated, 87.
To prevent shallow, 92.
Breathing exercises, 93.
Bronchus, 80.
Bulb, 291.
Caecum, 151, 158.
Calcium carbonate, 122.
Calcium phosphate, 122.
Calorie, defined, 126.
Cane sugar, 120.
Canines, 143.
Capillaries, 50, 64, 249.
Blood pressure at, 70.
Functions of, 51.
Work of, 174.
Carbohydrates, 119, 125.
Purpose served by, 121.
Storage of, 177.
Tests for, 135.
Carbon, 134.
Carbon dioxide,
Final disposition of, 111.
Preparation, 115.
Pressure, 110.
Properties, 110, 115.
Cardiac cycle, 46.
Cardiac orifice, 147.
Carpals, 227.
Carpus, 228.
Cell body, 283.
Functions of, 305.
Cell-division, 16.
Cell nucleus, 14.
Cell reproduction, 16.
Cell structure, 14.
Cell surroundings, 17.
Cell wall, 15.
Cells, 13-23.
Bone, how nourished, 220.
Ciliated epithelial, 81.
Food supply to, 180.
General work of, 17.
Importance of, 15.
Passage of materials to, 183.
Relation to nutrient fluid, 20.
Specialized, 197.
Special work of, 18.
Striated muscle, 244.
Cerebellum, 290.
Functions of, 317.
Cerebral functions, localization of, 318.
Cerebral hemispheres, 289.
Cerebral peduncles, 290.
Cerebrum, 288.
Functions of, 317.
Chlorine, 135.
Cholesterine, 155.
Chordae tendineae, 43.
Choroid coat, 375.
Chyme, 150.
Cigarettes, 333.
Cilia, 81.
To observe, 101.
Ciliary muscle, 375.
Ciliary processes, 375.
Circulation of blood, 40-64.
Causes of, 54.
Discovery of, by Harvey, 40.
Divisions of, 51, 52.
Effects of exercise upon, 63.
Effects of gravity upon, 64.
In a frog's foot, 64.
Organs of, 40-54.
Routes to, 174.
Coagulation,
Causes of, 31.
Purpose of, 32.
Time required for, 33.
Cochlea, 362.
Coffee,
Effects on complexion, 274.
Effects on digestion, 167.
Effects on heart, 56.
Colds, 193.
Serious nature of, 94.
To cure, 94.
Colon, parts of, 158.
Complexion, care of, 273.
Compound, defined, 104.
Conduction pathways, 286.
Conductivity, 304.
Condyloid joint, 232.
Conjunctiva, 373.
Consumption, _see_ Tuberculosis.
Control of arteries, 319.
Convolutions, 289.
Cooerdination, defined, 279.
Cornea, 375.
Corpora quadrigemina, 290.
Corpora striata, 289.
Corpus callosum, 289, 293.
Cortex, 288, 294.
Coughing, 81.
Cranial cavity, 7, 225.
Cranial nerves, 296.
Crura cerebri, 290.
Crystalline lens, 380.
Culex, 402.
Cytoplasm, 15.
Defects in focusing, 383.
Deformities of skeleton, 233-236.
Correction of, 236.
Prevention of, 235.
Deglutition, 145.
Steps in, 146.
Dendrites, 283, 306.
Dentine, 143.
Dermis, 264.
Dextrose, 30, 120, 150.
Diaphragm, 88.
To illustrate action of, 102.
Diastole, 46.
Diaxonic neuron, 283.
Diet, one-sided, 124.
Diffusion, 371.
Digestion, 130-172.
Hygiene of, 160.
Nature of, 130.
Not a simple process, 131.
Of fat, 156.
Purpose of, 177.
Stomach, 148.
Digestive fluids, 132.
Digestive organs, 160.
Table of, 138.
Digestive processes, 130, 141.
Illustrated, 137.
Diphtheria, 94, 405.
Care after, 211.
Disaccharides, 120.
Disease, 392-412.
Causes of, 393.
Eruptive, 405.
Precautions in recovery from, 407.
Prevention of, 393.
Dislocations, 239.
Dorsal-root ganglia, 295.
Drill, "setting up," 237.
Drugs, effects of, 35, 55, 129, 332.
Duodenum, 151.
Dura, 299.
Ear, 358.
Hygiene of, 365.
To demonstrate, 369.
Ear drum, 359.
Efferent neurons, 296.
Element, defined, 104.
Elevators of the ribs, 87.
Emetics, 151.
Emotional states, effects of, 330.
End bulbs, 342.
Endocardium, 42.
Endolymph, 361.
End-plate, 244.
End-to-end connections, 286.
Energy, 107, 186-196.
Bodily control of, 192.
From sun to cells, 191.
How plants store sun's, 189.
Increasing one's bodily, 194.
In food and oxygen, 190.
Kinds of, 186.
Methods of storing, 187, 188.
Transformation of, in muscle, 248, 249.
Enzymes, 132, 155.
Of the tissues, 184.
Epidermis, 264, 266.
Epiglottis, 80, 354.
Epithelium, 139.
Eruptive diseases, 405.
Esophagus, 146.
Eustachian tube, 359.
Excessive reading, 331.
Excitant impulse, 305.
Excretion, 197-213.
Defined, 18.
Necessity for, 201.
Exercise, 256, 257, 328, 409.
General rules for, 259.
Results of, 257.
Exhaustion, nervous, 211.
Results of, 195.
External ear, 358.
External stimuli, action of, 307.
Eye, 370-391.
Eyeball, 373.
Chambers of, 377.
Focusing power of, 378.
Movements of, 381.
Eyelids, 373.
Eyes,
Care of, 386.
Removal of foreign bodies from, 387,
Strong chemicals in, 388.
Eye strain, 211.
And disease, 385.
Fat, 30, 149, 162.
Digestion of, 156.
Emulsification of, 157.
Purpose served by, 121.
Route taken by, 175.
Tests for, 137.
Where stored, 178.
Fatty acid, 156.
Fenestra ovalis, 361.
Fenestra rotunda, 363.
Ferments, _see_ Enzymes.
Fibrin, 31.
Fibrin ferment, 32.
Fibrinogen, 30, 31.
Fissures, 289.
Food, 117-137.
Advantages of coarse, 167.
Classes of, 118, 119.
Composition of, 124.
Dangers from impure, 165.
Defined, 117.
Elements supplied by, 134.
Excess of proteid, 208.
Frequency of taking, 165.
Materials, table of, 126, 126.
Nitrogenous, 119.
Order of taking, 161.
Preparation of, 164.
Purity of, 128.
Quantity of, 164.
Simple, 118.
Variety, 128.
With reference to digestive changes, 132.
Foot lever, diagram of, 253.
Foot-pound, 196.
Foot-wear, hygienic, 238.
Fractures, treatment of, 239.
Fumigation, 400.
Furniture, school, 236.
Gall bladder, 154.
Ganglia, 281.
Dorsal-root, 295.
Sympathetic, 298.
Gastric glands, 147.
Gastric juice, to illustrate action of, 172.
Gelatine, 218.
Germ diseases, avoidance of, 394.
Germs, 29, 394, 395.
How spread, 395.
Glands, 197-213.
Digestive, 140.
Ductless, 208.
Excretory, work of, 201.
Gastric, 147.
Kinds of, 197, 198.
Lymphatic, 68, 208.
Perspiratory, 206.
Salivary, 144.
Structure of, 197.
Thymus, 208.
Thyroid, 208.
Gliding joint, 232.
Glottis, 355.
Glycogen, 120, 177.
Grape sugar, tests for, 120, 136.
Gross anatomy, defined, 1.
Gullet, 146.
Gustatory pore, 345.
Gustatory stimulus, 345.
Habits, 315, 334.
Hair, 267.
Care of, 276.
Hair cells, 363.
Hair follicle, 267.
Haversian canals, 219.
Hearing, defective, 366.
Heart, 41.
Care of, 55.
Connection with arteries and veins, 45.
Difference in parts of, 44.
How it does its work, 45.
Observations on, 60, 61, 62.
Sounds of the, 47.
Valves of, 43.
Heart muscle, structure of, 247.
Heat and cold, effects of, 330.
Hemoglobin, 26.
Hepatic artery, 154.
Hepatic veins, 154.
Hindbrain, 290.
Hinge joint, 231.
Histology, defined, 1.
Humerus, 227.
Hyaloid membrane, 378.
Hydrochloric acid, 149, 150.
Hydrogen, 134.
Hygiene,
Defined, 2.
General aim of, 2.
General laws of, 2, 392.
Of digestion, 160.
Of skeleton, 238.
Relation of physiology and anatomy to, 3.
Hygienic housekeeping, 399.
Hypoglossal nerves, 298.
Ileo-caecal valve, 151.
Ileum, 151.
Images,
Diagram illustrating, 372.
Formation of, 371.
Incisors, 143.
Incus, 359.
Infectious diseases, 394.
Infundibula, 80, 84.
Inhibitory impulse, 305.
Insomnia, 329.
Inspiratory force, 70.
Intercellular material, production of, 13, 18.
Internal ear, 360.
Intestinal juice, 152, 157.
Iris, 375.
Iron, 135.
Irritability, 6, 243, 304.
Isolation, 406.
Jejunum, 151.
Joints, 230-232, 242.
Kidneys, 201.
Blood supply to, 204.
Cortex of, 204.
Inflammation of, 211.
Pelvis of, 202.
Structure, 202.
Symptoms of diseased, 211.
Work of, 205.
Knee jerk reflex, 322.
Lachrymal glands, 383.
Lacteals, work of, 174.
Lacunae, 220.
Laminae, 220.
Large intestine, 157.
Division of, 158.
Work of, 159.
Larynx, 80, 353-357.
To show plan of, 368.
Lever, 251.
Application to the body, 251.
Classes of, in body, 251.
Producing motion, diagram of, 252.
To show action of, 252.
Leucocytes, 27.
Levulose, 120, 150.
Life, maintenance of, 20.
Light, 370, 371.
Simple properties, illustrated, 389.
Light waves, diagram illustrating passage of, 370.
Lime water, to prepare, 101.
Liver, 52, 152-155, 178.
Protection of, 210.
Work of, 206.
Lockjaw, 276.
Longsightedness, 384.
Lung capacity, diagram illustrating, 89.
Lung diseases, out-door cure for, 98.
Lungs, 77-103.
Capacity of, 88.
Changes air undergoes in, 101.
Excretory work of, 207.
Interchange of gases in, 88.
Observations of, 100.
Supply of blood to, 82.
To estimate capacity of, 103.
Weakest portions of, 92.
Lymph, 65-75.
Composition, 66.
Movements at the cells, 71.
Origin of, 65.
Physical properties, 66.
Where it enters the blood, 70.
Lymph movements, causes of, 69.
Lymph spaces, 66.
Lymph vessels, 66.
Variable pressure on the walls of, 70.
Magnesium, 135.
Malarial fever, 401.
Malleus, 359.
Malpighian capsules, 203.
Maltose, 120.
Massage, 259.
Mastication,
Muscles of, 144.
Slow, 145.
Thorough, 160.
To show importance of, 171.
Matrix, 267.
Measles, 94.
Care after, 211.
Median fissures, 289.
Medulla oblongata, 291.
Medullary sheath, 284.
Membrana tympani, 358.
Membrane,
Active, 173.
Basement, 197.
Basilar, 363.
Membranous capsule, 377.
Membranous labyrinth, 361.
Mesentery, 152.
Metacarpals, 227.
Midbrain, 289.
Middle ear, 359.
Purposes of, 360.
Milk sugar, 120.
Mineral salts, 30.
Uses, 121.
Moderate drinkers, 333.
Molars, 143.
Molecules, defined, 105.
Mon-axonic neuron, diagram of, 282.
Mono-saccharides, 120.
Mosquitoes, 401-403.
Remedies against, 402.
Mouth, 141.
Movable joints,
Kinds of, 231.
Structure of, 230.
Mucous membrane, 80, 264.
Mucus, 139.
Muscle organ, 245.
Muscles, 243-263.
Alimentary, 189.
Important, 254-256.
Intercostal, 87.
Of mastication, 144.
Properties of, 243.
Muscular force, plan of using, 249.
Muscular sensations, 344.
Muscular stimulus, 248.
Muscular stimulus and contraction, to illustrate, 261.
Muscular tissue, kinds of, 243, 244.
Nails, 267.
Care of, 276.
Nasal duct, 383.
Neck exercise, 328.
Nerve cells, 281, 282.
Nerve fibers, 282, 293, 294.
Nerve path, diagram of, 286.
Nerve pathways, to demonstrate, 322.
Nerves, 281.
Nerve skeleton, 280.
Diagram of, 281.
Nerve stimuli, 306.
Nerve trunks, 281.
Nervous activity, wasteful forms of, 325.
Nervous control of,
Body temperature, 320.
Circulation of blood, 318.
Respiration, 320.
Nervous energy, economizing of, 315.
Nervous impulse, 248, 305.
Nervousness, 326.
Nervous system, 279-337.
Diagram of, 287.
Dissection of, 302.
Divisions of, 287.
Hygiene of, 324-337.
Nature of, 287.
Physiology of, 304-323.
Work of, 280.
Neural arch, 224.
Neurilemma, 284.
Neurons, 281, 282.
Arrangement of, 284, 293.
Diagram, illustrating, 285.
Properties of, 304.
Nicotine,
Effects of, 333.
Relation of age to effects, 333.
Nitrogen, 134.
Non-striated cells, to show, 261.
Non-striated muscles,
Purpose of, 246.
Structure of, 246.
Work of, 247.
Normal temperature, 269.
Nosebleed, 58.
Nucleoplasm, 14.
Nutrients (_see_ Foods),
Composition of, 135.
Relative quantity needed, 123.
Routes taken by, 175.
Tests for, 136.
Nutriment, storage of, 177-180.
Olfactory stimulus, 347.
Opsonins, 34.
Optic thalami, 289.
Orbit, 373.
Organ, defined, 7.
Organism, defined, 19.
Organization, defined, 10.
Osmosis, 72.
At the cells, 72.
To illustrate, 75.
Ossein, 218.
Overstudy, 211.
Oxidation, defined, 106.
Oxygen, 104-117.
Combined, 105, 113.
Free, 105, 113.
How it unites, 105.
Main uses of, 108.
Movement a necessity, 106, 108, 115.
Movement in body, 106, 108, 115.
Nature of, 104.
Passage of, from cells, 110.
Passage of, through blood, 109.
Passage of, toward cells, 109.
Preparation of, 113.
Pressure, 109.
Properties of, 113.
Purpose of, in the body, 106.
Oxyhemoglobin, 27.
Pacinian corpuscles, 342, 343.
To demonstrate, 348.
Pancreas, 155.
Pancreatic juice, 155.
Papillae, 266.
Patent medicines, 166.
Pelvic girdle, 226.
Pepsin, 149.
Peptones, 149, 176.
Pericardium, 41.
Perilymph, 361.
Perimysium, 245.
Periosteum, 218.
Peritoneum, 180.
Perspiration, 207.
Pharynx, 145.
Openings into, 145, 146.
Phosphorus, 135.
Phrenic nerve, 302.
Physiological salt solution, 38.
Physiology, defined, 2.
Pia, 299.
Pigment granules, 266.
Pinna, 358.
Pitch, detection of, 365.
Pivot joint, 232.
Plasma, 25, 29.
Pleura, 84.
Plexus, 281.
Pneumonia, 94.
Pons, 290.
Pons Varolii, 290.
Portal vein, 154.
Primitive sheath, 284.
Proteids, 161.
Circulating, 179.
Kinds of, 118.
Purposes of, 119.
Supplied by, 125.
Tests for, 135, 136.
Tissue, 179.
Proteoses, 149, 176.
Protoplasm, 14.
Protozoa, 394.
Ptyalin, 145.
Public sanitation, 396.
Pulp cavity, 143.
Pupil, 375.
Pure food law, 128.
Pus, 28, 29.
Pyloric orifice, 147.
Pyramids, 202.
Quarantine, 406.
Radius, 227.
Reaction time, to determine, 323.
Reading glasses, 386.
Receptacle of the chyle, 68, 170.
Rectum, 158.
Red corpuscles, 25.
Disappearance of, 27.
Function of, 26.
Origin of, 27.
To examine, 38.
To prepare models of, 39.
Red marrow, 219.
Reenforcement of sound, 352, 356, 368.
Reflection, kinds of, 371.
Reflex action, 308.
Diagram illustrating, 310.
In circulation of blood, 311.
In digestion, 310.
Purposes of, 311.
Reflex action and mind, 308.
Reflex action pathway, 309.
Refraction, 371.
Rennin, 149.
Respiration, 76-103.
Artificial, 97.
Internal, 89.
Lung, 76.
Retina, 376.
Retinitis, 333.
Rheumatism,
Effects on the heart, 56.
Sequel to other diseases, 407.
Right lymphatic duct, 67.
Rods and cones, 377.
Rods of Corti, 364.
Sacrum, 224.
Saliva, 145.
Composition of, 145.
Uses of, 145.
To show action on starch, 171.
Salivary glands, 144.
Kinds of, 144.
Reflex action of, 323.
Sanitation, defined, 2.
Sarcolemma, 244.
Sarcoplasm, 244.
Scala media, 363.
Scala tympani, 363.
Scala vestibula, 363.
Scarlet fever, care after, 211.
Sciatic nerve, 302.
Sclerotic coat, 374.
Secondary reflex action, 314.
Secretions, 197.
Kinds of, 200.
Secretory process, nature of, 199.
Seeing, problem of, 372.
Self-control, 326, 334.
Habit of, 325.
Semicircular canals, 362.
Semilunar valves, 44.
Sensations, 338-349.
Classes of, 339.
Production of, 338, 349.
Purposes of, 340.
Special, 340.
Sensations (_continued_).
Steps in production of, 341.
Sensation stimuli, 339.
Sense organs, simple forms of, 341, 342
Serous coat, 140, 148.
Serous membrane, 264.
Serum albumin, 30.
Serum globulin, 30.
Shortsightedness, 384.
Shoulder girdle, 226.
Sight, organs of, 373.
Sigmoid flexure, 158.
Simple life, 410.
Skeleton, 216-243.
How deformed, 234.
Hygiene of, 233.
Plan of, 221.
Purpose of, 221.
Skin, 264-277.
As regulator of temperature, 270.
Experiments on, 349.
Functions of, 267, 268.
Observations on skin, 278.
Skin wounds, treatment of, 275.
Skull, 225.
Sleep, 329.
Small intestine, 151.
Mucous membrane of, 151.
Muscular coat of, 152.
As organ of absorption, 173.
Parts of, 151.
Serous coat of, 152.
Work of, 157.
Smell,
Sensation of, 346.
Value of, 347.
Sneezing, 81.
Sodium, 135.
Sodium carbonate, 155.
Sodium chloride, 122.
Soft palate, 141.
Solution, 131.
Kinds of, 73.
Solution theory, 156.
Solvents, 131.
Sound,
To illustrate origin of, 367.
To show transmission of, 367.
Sound waves,
As stimuli, 331.
Nature of, 350.
Reenforcement of, 352.
To show effects of, 368.
Value of, 353.
Speech, production of, 357.
Spinal column, 223-225.
Hygiene of, 233.
Spinal cord, 280.
Protection of, 299.
Spinal nerves, 295.
Double nature of, 295.
Spitting, 403.
Spleen, 208.
Sprains, 239, 240.
Stapes, 359.
Starch, 162.
Action of, on saliva, 171.
Animal, 120.
Tests for, 136.
Steapsin, 155, 156.
Stegomyia, 403.
Sternum, 225.
Stomach, 147.
Mucous membrane of, 147.
Muscular action of, 150.
Muscular coat, 148.
Serous coat, 148.
Storage of nutriment, 177-179.
"Strenuous life," 410.
Striated fibers, to show, 261.
Striated muscles, to show, 261.
Stroma, 25.
Sugars, kinds, 120.
Sulphur, 135.
Supra-renal bodies, 208.
Suspensory ligament, 377.
Sutures, 230.
Sympathetic ganglia and nerves, 298.
Work of, 316.
Synovial fluid, 231.
Synovial membrane, 231.
System, defined, 20.
Systole, 46.
Taste buds, 345.
Tea,
Effects on digestion, 167.
Effects on heart, 56.
Tears, 383.
Teeth, 142.
Care of 163.
Kinds of, 143.
Temperature,
Body, 207.
Corpuscles, 271, 345.
Sensation, 343.
Tendon of Achilles, 256.
Tendons, 246.
Tests for foods, 136, 137.
Tetanus, 262, 275.
Thoracic cavity, 7, 85, 100, 102.
Thoracic duct, 67, 170.
Thorax, 85.
Bones of, 225.
Tissue enzymes, 182.
Tissues, 4.
Complex nature of, 13.
Defined, 20.
General purposes of, 5.
Kinds of, 5, 6.
Observations on, 12.
Properties of, 6.
Tobacco, effect on heart, 56.
"Tobacco heart," 56, 333.
Tongue, 143.
Tonic bath, 273.
Touch, 343.
Touch corpuscles, 342.
Toxins, 394.
Trachea, 80.
Trypsin, 155, 156.
Tuberculosis, 90, 92, 94, 98.
How communicated, 403.
Outdoor treatment, 98.
To prevent, 404.
Tympanum, 359.
Typhoid fever, 404, 407.
Ulna, 227.
Urea, 110, 205, 207, 210.
Ureters, 170.
Uriniferous tubules, 203.
Vaccination, 406.
Valves,
Advantages of, in veins, 49, 63.
Mitral, 43.
Position of, in veins, 63.
Purposes of, 49, 63.
Tricuspid, 43.
Veins, 47.
Functions of, 51.
Renal, 202.
Ventilation, 94.
Rules for, 95, 96.
Ventricles, 42.
To illustrate action of, 62.
Vermiform appendix, 158.
Vertebrae, 223-225.
Interlocking of, 225.
Joining of, 224.
Kinds, 223.
Vestibule, 361.
Villi, 152.
Parts of, 173, 174.
Visual perceptions, 382.
Visual sensations, 382.
Vitreous humor, 378.
Vocal cords, 355.
Voice, 353-357.
How produced, 356.
Pitch and intensity, 356.
Voluntary action, 311, 312.
Voluntary action pathways, 312.
Vomiting, 151, 152.
Waste material, passage from body, 210.
Wastes, 30.
Water,
Importance of, 123.
Supply of, 398.
Value of, 210.
Water-vapor, 208.
White corpuscles, 27, 28.
Functions of, 29.
To examine, 39.
Work,
Hygienic value of, 328, 409.
Worry, 211.
Yellow fever, 403.
Yellow marrow, 218.
Yellow spot, 377.
FOOTNOTES
1 The body is affected by what it does (exercise, work, sleep), by
things taken into it (food, air, drugs), and by things outside of it
(the house in which one lives, climate, etc.). That phase of hygiene
which has for its object the making of the surroundings of the body
healthful is known as _sanitation_.
2 When classified according to their essential structure, the tissues
fall into four main groups: epithelial and glandular tissue,
muscular tissue, nervous tissue, and connective tissue. According to
this system the osseous, cartilaginous, and adipose tissues are
classed as varieties of connective tissue. See page 18.
3 The properties of substances are the qualities or characteristics
(color, weight, etc.) by means of which they are recognized.
4 Certain of these cells also form deposits of fat, giving rise to the
adipose, or fatty, tissue.
5 Any organized structure, such as the body, whose parts are pervaded
by a common life, is known as an _organism_. The term "organism" is
frequently applied to the body.
6 In birds, reptiles, amphibians, and fishes the red corpuscles have
nuclei (Fig. 9).
7 The micron is the unit of microscopical measurements. It is equal to
1/1000 of a millimeter and is indicated by the symbol {~GREEK SMALL LETTER MU~}.
8 The peculiar shape of the red corpuscle has no doubt some relation
to its work. Its circular form is of advantage in getting through
the small blood vessels, while its extreme thinness brings all of
its contents very near the surface--a condition which aids the
hemoglobin in taking up oxygen. If the corpuscles were spherical in
shape, some of the hemoglobin could not, on account of the distance
from the surface, so readily unite with the oxygen.
9 The coloring matter of the bile consists of compounds formed by the
breaking down of the hemoglobin; the spleen contains many large
cells that seem to have the power first of "engulfing" and later of
decomposing red corpuscles. A further evidence that the spleen aids
in the removal of worn-out corpuscles is found in the fact that
during diseases that cause a destruction of the red corpuscles, such
as the different forms of malaria, the spleen becomes enlarged.
10 An infected part of the body, such as a boil or abscess, should
never be bruised or squeezed until the time of opening. Pressure
tends to break down the wall of white corpuscles and to spread the
infection. Pus from a sore contains germs and should not, on this
account, come in contact with any part of the skin. (See treatment
of skin wounds, Chapter XVI.)
11 Coagulation is not confined to the blood. The white of an egg
coagulates when heated and when acted upon by certain chemicals, and
the clabbering of milk also is a coagulation.
12 If the blood be stirred or "whipped" while it is coagulating, the
clot may be broken up and the fibrin separated as fast as it forms.
The blood which then remains consists of serum and corpuscles and
will not coagulate. It is known as "defibrinated" blood.
13 Certain substances, called _opsonins_, have recently been shown to
exist in the plasma, that aid the white corpuscles in their work of
destroying germs. The opsonins appear to act in such a manner as to
weaken the germs and make them more susceptible to the attacks of
the white corpuscles.
14 Some of the changes in the blood are very closely related to our
everyday habits and inclinations. For example, a lack of nourishment
in the blood causes hunger and this leads to the taking of food. If
the fluids of the body become too dense, a feeling of thirst is
aroused which prompts one to drink water.
15 Metchnikoff, _The New Hygiene_.
16 A physiological salt solution is prepared by dissolving .6 of a gram
of common salt in 100 cc. of distilled water or pure cistern water.
This solution, having the same density as the plasma of the blood,
does not act injuriously upon the corpuscles.
17 The term "circulation" literally means moving in a circle. While the
blood does not move through the body in a circle, the term is
justified by the fact that the blood flows out continually from a
single point, the heart, and to this point is continually returning.
18 The heart at first glance seems to bear little resemblance to the
pumps in common use. When it is remembered, however, that any
contrivance which moves a fluid by varying the size of a cavity is a
pump, it is seen that not only the heart, but the chest in breathing
and also the mouth in sucking a liquid through a tube, are pumps in
principle. The ordinary syringe bulb illustrates the class of pumps
to which the heart belongs. (See Practical Work.)
19 The contraction of the heart is known as the _systole_ and its
relaxation as the _diastole_. The systole plus the diastole forms
the so-called "cardiac cycle" (Fig. 18). This consists of (1) the
contraction of the auricles, (2) the contraction of the ventricles,
and (3) the period of rest. The heart systole includes the
contraction of both the auricles and the ventricles.
20 Martin, _The Human Body_.
21 The pressure maintained by the left ventricle has been estimated to
be nearly three and one half pounds to the square inch--a pressure
sufficient to sustain a column of water eight feet high. The
pressure maintained by the right ventricle is about one third as
great. In maintaining this pressure the heart does a work equal to
about one two-hundredth of a horse power.
22 The location of the heart in the thoracic cavity causes movements of
the chest walls to draw blood into the right auricle for the same
reason that they "draw" air into the lungs.
23 Active exercise through short intervals, followed by periods of
rest, such as the exercise furnished by climbing stairs, or by short
runs, is considered the best means of strengthening the heart.
24 Nosebleed in connection with any kind of severe sickness should
receive prompt attention, since a considerable loss of blood when
the body is already weak may seriously delay recovery.
25 Newton, _Practical Hygiene_.
26 On account of its position in the body, the lymph is not easily
collected for examination. Still, nearly every one will recall some
experience that has enabled him to see lymph. The liquid in a water
blister is lymph, and so also is the liquid which oozes from the
skin when it is scraped or slightly scratched. Swelling in any part
of the body is due to the accumulation of lymph at that place.
27 In certain small animals of the lowest types a single liquid,
serving as a medium of exchange between the cells and the body
surface, supplies all the needs of the organism. In larger animals,
however, where materials have to be moved from one part of the cell
group to another, a portion of the nutrient fluid is used for
purposes of transportation. This is confined in channels where it is
set in motion by suitable organs. The portion which remains outside
of the channels then transfers material between the cells, on the
one hand, and the moving liquid, on the other.
28 Surgeons in opening veins near the thoracic cavity have to be on
their guard to prevent air from being sucked into them, thereby
causing death.
29 Oxygen forms about 21 per cent of the atmosphere, nitrogen about 78
per cent, carbon dioxide about .03 per cent, and the recently
discovered element argon about 1 per cent. The oxygen is in a
_free_, or uncombined, condition--the form in which it can be used in
the body.
30 The peculiar work devolving upon the organs of respiration
necessitates a special plan of construction--one adapted to the
properties of the atmosphere. Being concerned in the movement of
air, a gaseous substance, they will naturally have a structure
different from the organs of circulation which move a liquid (the
blood). All the organs of the body are adapted by their structure to
the work which they perform.
31 In ordinary inspirations the force that causes the air to move
through the passages is scarcely an ounce to the square inch, while
in forced inspirations it does not exceed half a pound. On this
account the closing of any of the air passages by pressure, or by
the presence of foreign substances, would keep the air from reaching
some part of the lungs.
32 Coughing, which is a forceful expulsion of air, has for its purpose
the ejection of foreign substances from the throat and lungs.
Sneezing, on the other hand, has for its purpose the cleansing of
the nostrils. In coughing, the air is expelled through the mouth,
while in sneezing it is expelled through the nostrils.
33 The amount of dust suspended in what we ordinarily think of as pure
air is shown when a beam of direct sunlight enters an otherwise
darkened room.
34 Some children find it difficult to breathe through the nostrils on
account of growths (called adenoids) in the upper pharynx. Such
children should have medical attention. The removal of these growths
not only improves the method of breathing, but in many instances
causes a marked improvement in the general health and personal
appearance.
35 The weakest portions of the lungs appear to be the tiny lobes at the
top. As they occupy the part of the thorax most difficult to expand,
air penetrates them much less freely than it does the lobes below.
In most cases of consumption (some authorities give as high as
eighty per cent), the upper lobes are the first to be affected. Flat
chests and round shoulders, by increasing this natural difficulty in
breathing, have long been recognized as causes which predispose to
consumption.
36 The following exercise, from Dudley A. Sargent's _Health, Strength,
and Power_, will be found most beneficial: "Stand with the feet
together, face downward, arms extended downward, and backs of the
hands touching. Raise the hands, arms, and elbows, keeping the backs
of the hands together until they pass the chest and face. Then
continue the movement upward, until the hands separate above the
head with the face turned upward, when they should be brought
downward and outward in a large circle to the starting point. Begin
to inhale as the arms are raised and take in as much air as possible
by the time the hands are above the head, then allow the breath to
go out slowly as the arms descend."
37 Colds may frequently be broken up at their beginning by taking a
prolonged _hot_ bath and going to bed. After getting a start,
however, they run a course of a few days, a week, or longer,
depending upon the natural vigor of the individual and the care
which he gives his body during the time. In throwing off a cold, the
following suggestions will be found helpful:
1. Dress warmly (without overdoing it) and avoid getting chilled. 2.
Diminish the usual amount of work and increase the period for sleep.
If very weak, stay in bed. Save the energy for throwing off the
cold. 3. If able to be about, spend considerable time in light
exercise out of doors, but avoid getting chilled. 4. Keep the bowels
active, taking a cathartic if necessary. 5. To relieve pain in the
chest, apply a mustard plaster or a flannel cloth moistened with
some irritating substance, such as turpentine or a mixture of equal
parts of kerosene and lard. Keep up a mild irritation until the pain
is relieved, but avoid blistering.
38 Not only do the lungs remove oxygen from the air and add carbon
dioxide to it, but they separate from the body considerable moisture
and, according to some authorities, a small amount of an impurity
referred to as "animal matter." Odors also arise from the skin,
teeth, and clothing which, if not dangerous to the health, are
offensive to the nostrils. If on going into a room such odors are
detected, the ventilation is not sufficient. This is said to be a
reliable test.
39 E.A. Schaffer, "Artificial Respiration in its Physiologic Aspects,"
_The Journal of the American Medical Association_, September, 1908.
40 Testing the prone-posture method by suitable apparatus, Professor
Schaffer has found it capable of introducing more air per minute
into the lungs than any of the other methods of artificial
respiration, and more even than is introduced by ordinary breathing.
41 Osier, _The Principles and Practice of Medicine_.
42 Huber, _Consumption and Civilization_.
43 To prepare limewater some small lumps of _fresh_ lime (either
slacked or unslacked) are added to a large bottle of water and
thoroughly shaken. This is put aside until the lime all settles to
the bottom and the water above is perfectly clear. This is now ready
for use and may be poured off as needed. When the supply is
exhausted add more water and shake again.
44 An _element_ is a single kind of matter. Those substances are
classed as elements which cannot be separated into different kinds
of matter. Two or more elements combined in definite proportions by
weight form a _compound_. The elements are few in number, only about
eighty being known. Compounds, on the other hand, are exceedingly
numerous.
45 The term _energy_, as used here, has the same general meaning as the
word _power_. See Chapter XII.
46 The oxygen pressure of the atmosphere is that portion of the total
atmospheric pressure which is due to the weight of the oxygen. Since
oxygen comprises about one fifth of the atmosphere, the pressure
which it exerts is about one fifth of the total atmospheric
pressure, or, at the sea level, about three pounds to the square
inch (15 x 1/5 = 3). This is the oxygen pressure of the atmosphere.
The low oxygen pressure in the tissues is due to its scarcity, and
this scarcity is due to its entering into combination at the cells.
47 See footnote on oxygen pressure, page 109.
48 The impression prevails to some extent that carbon dioxide, on
account of its weight, settles out of the atmosphere, collecting in
old wells and at the floor in crowded rooms. Any such settling of
the carbon dioxide is prevented by the rapid motion of its
molecules. This motion not only prevents a separation of carbon
dioxide and air after they are mixed, but causes them to mix rapidly
when they are separated, if they still have surface contact. The
carbon dioxide found in old wells is formed there by decaying
vegetable or animal matter. In rooms it is no more abundant at the
floor than in other parts.
49 On account of the formation of carbon dioxide in places containing
decaying material, the descent into an old well or other opening
into the earth is often a hazardous undertaking. Before making such
a descent the air should always be tested by lowering a lighted
lantern or candle. Artificial respiration is the only means of
restoring one who has been overcome by this gas (page 97).
50 While awaiting oxidation at the cells, the carbohydrates and fats
are stored up by the body, the carbohydrates as glycogen and the
fats as some form of fat. In this sense they are sometimes looked
upon as serving to build up certain of the tissues.
51 The following table shows the main elements in the body and their
relation to the different nutrients:
[Nutrient Table]
52 The recently advanced theory that the molecules of the mineral
salts, by dissolving in water, separate into smaller divisions, part
of which are charged with positive electricity and part with
negative electricity, has suggested several possible uses for sodium
chloride and other mineral salts in the body. The sodium chloride in
the tissues is in such concentration as to be practically all
separated into its sodium and chlorine particles, or ions. It has
recently been shown that the sodium ions are necessary for the
contraction of the muscles, including the muscles of the heart.
There is also reason for believing that the different ions may enter
into temporary combination with food particles, and in this way
assist in the processes of nutrition.
53 Chittenden, _The Nutrition of Man_.
54 Compiled from different sources, but mainly from Atwater's _Foods:
Nutritive Value and Cost_, published by the U.S. Department of
Agriculture.
55 The calorie is the adopted heat unit. As used in this table it may
be defined as the quantity of heat required to raise 1 kilogram (2.2
pounds) of water, 1 degree centigrade. The calories also show the
relative amount of energy supplied by the different foods.
56 While alcohol cannot be classed as a food, it is believed by some
authorities to contain _food value_ and, in the hands of the
physician, to be a substance capable of rendering an actual service
in the treatment of certain diseases. It might, for example, be used
where one's power of digestion is greatly impaired, since alcohol
requires no digestion. But upon this point there is a decided
difference of opinion. Certain it is that no one should attempt to
use alcohol as food or medicine except under the advice and
direction of his physician.
57 A layer of connective tissue between the mucous membrane and the
muscular coat is usually referred to as the _submucous_ coat. This
contains numerous blood vessels and nerves and binds the muscular
coat to the mucous membrane.
58 The saliva may continue to act for a considerable time after the
food enters the stomach. "Careful examination of the contents of the
fundus (large end of the stomach) by Cannon and Day has shown that
no inconsiderable amount of salivary digestion occurs in the
stomach."--FISCHER, _The Physiology of Alimentation_.
59 Perhaps the simplest method of inducing vomiting is that of
thrusting a finger down the throat. To make this method effective
the finger should be held in the throat until the vomiting begins.
An emetic, such as a glass of lukewarm salt water containing a
teaspoonful of mustard, should also be taken, and, in the case of
having swallowed poison, the vomiting should be repeated several
times. It may even be advantageous to drink water and then vomit it
up in order to wash out the stomach.
60 Hammerstein, _Text-book of Physiological Chemistry._
61 Amylopsin is absent from the pancreatic juice of infants, a
condition which shows that milk and not starch is their natural
food.
62 The fact that butter is more easily digested than other fatty
substances is probably due to its consisting largely of a kind of
fat which, on splitting, forms a fatty acid (butyric) which is
soluble in water.
63 Fischer, _Physiology of Alimentation._
64 Beginning the meal with a little soup, as is frequently done, may be
of slight advantage in stimulating the digestive glands. To serve
this purpose, however, and not interfere with the meal proper, it
should contain little greasy or starchy material and should be taken
in small amount.
65 Dr. William Beaumont, an American surgeon of the last century, made
a series of observations upon a human stomach (that of Alexis St.
Martin) having an artificial opening, the result of a gunshot wound.
Much of our knowledge of the digestion of different foods was
obtained through these observations. In spite of the protests of his
physician, St. Martin would occasionally indulge in strong drink and
always with the same result--the lining of the stomach became much
inflamed and very sensitive, and the natural processes of digestion
were temporarily suspended.
66 The lacteals (from the Latin _lacteus_, milky) are so called on
account of their appearance, which is white, or milk-like, due to
the fat droplets.
67 Peptones and proteoses, when injected directly into the blood, are
found to act as poisons.
68 The soluble double sugars (maltose, milk sugar, and cane sugar) are
reduced to the simple sugars (dextrose and levulose). Furthermore
the action on the proteids does not stop with the production of
peptones and proteoses, but these in turn are still further reduced.
69 Energy, which is defined as _the ability to do work_, or _to cause
motion_, exists in two general types, or forms, known as kinetic
energy and as potential energy. _Kinetic_ energy is energy at work,
or energy in the act of producing motion; while _potential_ energy
is reserve, or stored, energy. All moving bodies have kinetic
energy, and all stationary bodies which have within them the
_capability_ of causing motion possess potential energy. A bent bow,
a piece of stretched rubber, a suspended weight, the water above a
mill dam, all have the capability of causing motion and all have
potential energy. Examples of kinetic energy are found in the
movements of machinery, in steam and electricity, in winds, and in
currents of water. Kinetic is the active, and potential the
inactive, form of energy.
70 As the atoms of hydrogen and oxygen that make up the molecules of
water separate, they unite with atoms of their own kind--the hydrogen
with hydrogen and the oxygen with oxygen atoms. Since these
combinations are weaker than those of the water molecules, energy is
required to bring about the change. But when hydrogen burns in the
oxygen, the change is from a weaker to a stronger combination. The
stored-up energy is then given up or becomes active.
71 In the evaporation of water, the energy of the sun is stored with
reference to the force of gravity. In evaporating, water rises as a
gas, or vapor, above the earth's surface, but on condensing into a
liquid, it falls as rain. It then finds its way through streams back
to the ocean. All water above the sea level is in such a position
that gravity can act on it to cause motion, and it possesses, on
this account, potential or stored-up energy. It is because of this
energy that rapids and waterfalls are such important sources of
power.
72 Energy, like matter, can neither be created nor destroyed. It can,
however, be transferred from one body to another and transformed
from one form to another form. Whenever work is done, energy is
transferred from the body doing the work, to the body upon which the
work is done. During this process there may, or may not, be a
transformation of energy. In turning a grindstone, kinetic energy is
passed to the stone and used without transformation, but in winding
a clock, the kinetic energy from the hand is transformed into
potential energy in the clock spring. Then as the clock runs down
this is retransformed into kinetic energy, causing the movements of
the wheels.
Not only is kinetic transformed into potential energy and _vice
versa_, but the different forms of kinetic energy (heat, light,
electricity, sound, and mechanical motion) are readily transformed
the one into the other. With suitable devices, mechanical motion can
be changed into heat, sound, or electricity; heat into motion and
light; and electricity into all the other forms of energy. These
transformations are readily explained by the fact that the different
varieties of kinetic energy are but different forms of motion (Fig.
84).
73 The simplest arrangement of the parts of a gland is that where they
are spread over a plain surface. This arrangement is found in serous
membranes, such as the pleura and peritoneum. These membranes,
however, are not called glands, but secreting surfaces.
74 In the oxidations that occur in the body it is not supposed that the
nutrients are immediately converted to carbon dioxide, water, and
urea. On the other hand, it is held that their reduction takes place
gradually, as the reduction of sugar by fermentation, and that the
wastes leaving the body are but the "end products" and show only the
final results.
75 Alcohol, if used in considerable quantity, leads to cirrhosis of the
liver and Bright's disease of the kidneys, both very dangerous
diseases. Dr. William Osler in his treatise, _The Practice of
Medicine_, states that alcohol is the chief cause of cirrhosis of
the liver. Dr. T.N. Bogart, specialist in kidney diseases, asserts
that one third of all the cases of Bright's disease coming under his
observation are caused by alcohol.
76 Hall, _The Purin Bodies_.
77 Review "Main Physiological Problems," page 21.
78 In the production of motion in the body, as well as in the
production of any kind of _purposeful_ motion outside of the body,
three conditions must be fulfilled. There is required, in the first
place, a mechanical device or machine which is so constructed as to
produce a certain kind of motion. In the second place, energy is
needed to operate this device. And, finally, there must be some
controlling force, by means of which the motion is made to
accomplish definite results. The driving of a horse hitched to a
wagon will illustrate these conditions. The wagon is the mechanical
device, the horse furnishes the energy, and the driver supplies the
controlling force. In this, as in most cases, the machinery, the
source of energy, and the controlling force are disconnected except
when at work; but in the body all three occur together in the same
structure.
79 The dependence of the outer layers of bone cells upon the periosteum
for nourishment causes a destruction of this membrane to affect
seriously the bone beneath, producing in many instances a decay of
the bone substance.
80 It has been claimed that the introduction of vertical writing has
reduced the number of cases of spinal curvature originating in the
schoolroom, and statistics appear to prove the claim. It is shown,
on the other hand, that unnatural positions also are unnecessary in
the slanting system of writing, and that in either system the pupil
who is permitted to do so is liable to assume an improper position.
81 Lovett, _Lateral Curvature of the Spine and Round Shoulders_.
82 See "Hygiene of Muscles," Chapter XV.
83 On account of the striations of these cells the muscles which they
form are called striated muscles.
84 The striated muscle cells, having many nuclei, are said to be
multi-nucleated.
85 Every movement in the body has its opposing movement. This is
necessary both on account of the work to be accomplished and for
preserving the natural form of the body.
86 The distance from the fulcrum to the power is called the _power-arm_
and the distance from the fulcrum to the weight is called the
_weight-arm_ (Fig. 115).
87 The foot in lifting the body on tiptoe appears at first thought to
be a lever of the second class, the body being the weight and the
toe serving as the fulcrum. However, if the distance which the body
is raised is compared with the distance which the muscle shortens,
it is found that the _supposed_ weight has moved _farther_ than the
power (Fig. 118). It will also be noted that the muscle which
furnishes the power is attached at its upper end to the "weight."
These facts show clearly that we are not here dealing with a lever
of the second class. The foot in this instance acts as a lever of
the first class with the fulcrum at the ankle joint and the toe
pressing against the earth, which is the _actual_ weight. Since the
earth is immovable, the body is lifted or pushed upward, somewhat as
a fulcrum support is made to move when it is too weak to hold up the
weight that is being lifted. In other words, we have the same lever
action in the foot in lifting the body as we have when one lies face
downward, and, bending the knee, lifts some object on the toes.
_ 88 Walking_ is considered one of the very best forms of counter-active
exercise for the brain worker (page 328).
89 The epidermis does not afford complete protection against chemicals,
many of them being able to destroy it quickly. The rule of washing
the skin immediately after contact with strong chemical agents
should always be followed.
90 "Rough calculations have placed the number of sweat glands on the
entire body at about 2,000,000." Rettger, _Studies in Advanced
Physiology_.
91 Heat also leaves the body by the lungs, partly by the respired air
and partly through the evaporation of moisture from the lung
surfaces. Respiration in some animals, as the dog, is the chief
means of cooling the body.
92 "The story is told of some woodsmen who were overtaken by a severe
snowstorm and had to spend the night away from camp; they had a
bottle of whisky, and, chilled to the bone, some imbibed freely
while others refused to drink. Those who drank soon felt comfortable
and went to sleep in their improvised shelter; those who did not
drink felt very uncomfortable throughout the night and could get no
sleep, but in the morning they were alive and able to struggle back
to camp, while their companions who had used alcohol were frozen to
death.... This, if true, was of course an extreme case; but it
accords with the universal experience of arctic travelers and of
lumbermen and hunters in the northern woods, that the use of alcohol
during exposure to cold, although contributing greatly to one's
comfort for the time being, is generally followed by undesirable or
dangerous results."--HOUGH AND SEDGWICK: _The Elements of Hygiene and
Sanitation_.
93 Foods that are difficult to digest, or which cause disturbances of
the digestive organs (a coated tongue being one indication), have a
bad effect upon the skin. It is in this way that the use of tea and
coffee by some people induces a sallow or "muddy" condition of the
complexion.
94 A most valuable antiseptic ointment is prepared by the druggist from
the following formula:
Lanolin, 25 grams.
Ichthyol, 6 grams.
Yellow vaseline, 20 grams.
This is applied as a thin layer on the surface, except in the case
of boils or abscesses. In treating these a heavy layer is spread
over the affected part and then covered with absorbent cotton or a
thin piece of clean cotton cloth.
95 In a larger sense adjustment includes all those activities by means
of which the body is brought into proper relations with its
environment, including the changes which the body makes in its
surroundings to _adapt them_ to its purposes.
96 Almost to the present time, physiologists have described the nervous
system as being made up of two kinds of structural elements which
were called _nerve cells_ and _nerve fibers_. The nerve cells were
supposed to form the ganglia and the fibers to form the nerves.
Recent investigators, however, employing new methods of microscopic
study, have established the fact that the so-called nerve cell and
nerve fiber are but two divisions of the same thing and that the
nervous system is made up of, not two, but one kind of structural
element. The term "neuron" is used to denote this structural
element, or _complete nerve cell_.
97 Many of the axons in the brain and spinal cord have no primitive
sheath. Axons without the medullary sheath are found in the
sympathetic nerves. These are known as non-medullated axons and they
have a gray instead of a white color.
98 The difference in weight between the brain of man and that of woman
is due mainly to the fact that man's body is, as a rule,
considerably larger than that of woman's.
99 The nervous tissues present, at different places, two colors--one
white, and the other a light gray. Great significance was formerly
attached to these colors, because it was supposed that they
represented two essentially different kinds of nervous matter. It is
now known that the protoplasm in all parts of the neuron
proper--cell-body, axis cylinder, and dendrites--has a grayish color,
while the coverings of most of the fibers are white. Hence gray
matter in any part of the nervous system indicates the presence of
cell-bodies, and white matter the presence of nerve fibers.
100 In very early life the spinal cord entirely fills the spinal cavity,
but as the body develops the cord grows less rapidly than the spinal
column, and, as a consequence, separates at the lower end from the
inclosing bony column.
101 Fibers passing between the spinal cord and the cerebrum cross to
opposite sides--most of them at the bulb, but many within the cord--so
that the right side of the cerebrum is connected with the left side
of the body, and _vice versa_. This accounts for the observed fact
that disease or accidental injury of one side of the cerebrum causes
loss of motion or of feeling in the opposite side of the body.
102 In general, _afferent_ neurons or fibers are those that convey
impulses _toward_ the central nervous system (brain and cord), while
_efferent_ neurons or fibers are those that convey impulses _from_
the central system.
103 At different times the nervous impulse has been regarded as a
current of electricity; as a progressive chemical change, likened to
that in a burning fuse; as a mechanical vibration, such as may be
passed over a stretched rope; and as a molecular disturbance
accompanied by an electrical discharge. The velocity of the nervous
impulse, which is only about one hundred feet per second, proves
that it is not a current of electricity. It takes place with little
or no exhaustion of the cell protoplasm and consequently is not due
to chemical action. And the loose, relaxed condition of the nerves
prevents their transmission of physical vibrations, like those on a
stretched rope. The view that the impulse is a progressive molecular
disturbance, accompanied by an electrical discharge, has much
evidence in its favor, but it has only recently been proposed and is
likely to be modified upon fuller investigation.
104 The surface of the body includes the linings of the air passages,
food canal, and certain cavities, as well as the external covering
or skin.
105 Derived from the Latin _re_, back, and _flectere_, to turn or bend.
106 A frog from which the brain has been removed is suspended with its
feet downward and free to move. If a toe is pinched, the foot is
drawn away, and if dilute acid, or a strong solution of salt, is
placed on the tender skin, the feet are moved as if to take away the
irritating substance. This of course shows that reflex action can
take place independently of the brain.
Now if the spinal cord is also destroyed, there is no response when
the irritation of the skin is repeated. The animal remains perfectly
quiet, because the destruction of the cord has interrupted the
reflex action pathway. This shows that some part of the central
nervous system is necessary to reflex action.
107 Review description of the spinal nerves, page 295.
108 Where a deep-seated cause for worry exists, there may be occasion
for grave concern. Many people have become insane through continued
worry about some _one_ thing. In cases of this kind the sufferer
needs the aid of sympathetic friends, and sometimes of the
physician, in getting the mind away from the exciting cause. A
change of scene, a visit, or some new employment is frequently
recommended, where the actual cause for the worry cannot be removed.
109 Any part of the body which is overworked or which works at a
disadvantage tends to disturb, more or less, the entire nervous
system and to produce nervousness. Especially is this true of such
delicate and highly sensitive structures as the eyes. If the eyes do
not focus properly or if the muscles that move the eyeballs are out
of their natural adjustment, extra work is thrown upon these
delicate parts. One of the first and sometimes the only indication
of eye strain is that of some disturbance of the nervous system. For
this reason it is important to carefully test the eyes in
determining the cause of nervousness (page 385).
110 One form of neck exercise recommended for this purpose is easily
taken on retiring at night. Lying flat on the back, without a
pillow, lift the head slowly from the bed and let it as slowly
settle back to the level of the body. Repeat several times, lying on
the back, and then again on the face and again on each side.
Practice these exercises every night during an interval of a month
or until relief is secured.
111 Insurance statistics show that habitual _moderate drinkers_ do not
live so long as abstainers.
112 Organs very frequently affected by tobacco are the heart and the
eyes. It induces, as already stated (page 56), a dangerous nervous
derangement called "tobacco heart," and it causes a serious disorder
of the retina (retinitis) which leads in some instances to loss of
vision. Tobacco smoke also acts as an irritant to the delicate
lining of the eyes, especially when the tobacco is smoked indoors.
113 Of 4117 boys in the Illinois State Reformatory, 4000 used tobacco,
and over 3000 were cigarette smokers. Dr. Hutchison, of the Kansas
State Reformatory, says: "Using cigarettes is the cause of the
downfall of more of the inmates of this institution than all other
vicious habits combined."
114 The term "mind" is used in this and preceding chapters in its
popular, not technical, sense.
115 The problem of social adjustment is but a phase of the general
problem of establishing proper relations between the body and its
surroundings.
116 A vibrating body is one having a to-and-fro movement, like that of a
clock pendulum or the string of a violin on sounding. Bodies to give
out sound waves must vibrate rapidly, making not less than sixteen
vibrations per second. The upper limit of hearing being about 40,000
vibrations per second, certain bodies may even vibrate too rapidly
to be heard.
117 Somewhat as the waves on a body of water impart motion to the sticks
and weeds along the shore, sound waves are able to cause bodies that
are small or that are delicately poised to vibrate.
118 Some idea of how the movements of the cartilages change the tension
of the cords may be obtained by holding the fingers on the larynx,
between the thyroid and cricoid cartilages, and making tones first
of low and then of high pitch. For the high tones the cartilages are
pulled together in front, and for the low tones they separate. As
they pull together in front, they of course separate behind and
above, where the cords are attached.
119 It is only the central portion of the pinna that aids the entrance
of sound into the auditory canal. If by accident the outer portion
of the pinna is removed, there is no impairment of the hearing.
120 The middle ear is also called the _ear drum_, and, by the same
system of naming, the membrana tympani is referred to as the _drum
membrane_.
121 The inner projection of the temporal bone is known as the petrous
process.
122 A small opening in the bone at this place is called the _fenestra
rotunda_.
123 Consult some work on physics on the different kinds of lenses and
their uses.
124 With respect to its adjustments the eye does not differ in principle
from various other optical instruments, such as the microscope,
telescope, photographer's camera, etc., which, in their use, form
images of objects. These all require some adjustment of their parts,
called focusing, which adapts them to the distance. The eye's method
of focusing, however, differs from that of most optical instruments,
in that the adjustment is brought about through changes in the
curvature of a lens.
125 The converging power of convex lenses varies as the curvature--the
greater the curvature, the greater the converging power.
126 An oculist is a physician who specializes in diseases of the eye.
127 Some of the more common symptoms of eye strain are nervousness,
headache, insomnia, irritations of the eyelids, sensitiveness to
bright light, and pain in the use of the eyes.
128 Pyle, _Personal Hygiene_.
129 "An infectious disease is one in which disease germs infect (that
is, invade) the body from without. Among the infectious diseases are
some that are quite directly and quickly conveyed from person to
person and to these the term contagious is applied. Formerly a sharp
line was drawn between infection and contagion, but to-day it is
recognized that no such line exists."--HOUGH AND SEDGWICK, _The
Elements of Hygiene and Sanitation._
130 The arctic explorer, Nansen, states that during all the time that
his party was exposed to the low temperature of the arctic region,
no one was attacked by a cold, but on returning to a warmer climate
they were subject to colds as usual. The difference he attributes to
the absence of germs in the severe arctic climate. There seems to be
no doubt but that most of our common colds are due to attacks of
germs.
131 An interesting biological fact is that the female _Anopheles_, and
not the male, sucks the blood of animals and is the cause of the
spreading of malaria.
132 The habit of spitting upon the floors of public buildings and street
cars, and also upon sidewalks, is now recognized as a most dangerous
practice. Not only consumptives, but people with throat affections,
may do no end of harm in the spreading of disease by carelessness in
this respect.
133 For further information on the care of consumptives, consult Huber's
_Consumption and Civilization_.
134 As typhoid fever is a disease of the small intestine, great care
must be exercised in taking food and in the bodily movements. Solids
greatly irritate the diseased lining of the intestine, and the
weakened walls may actually be broken through by pressure resulting
from moving about.
135 Alcoholic beverages include all the various kinds of drinks that owe
their stimulating properties to a substance, ethyl alcohol (C2H5OH),
which is made from sugar by the process of fermentation. They
include _malt liquors_, such as beer and ale, which contain from
three to eight per cent of alcohol; _wines_, such as claret, hock,
sherry, and champagne, which contain from five to twenty per cent of
alcohol; and _distilled liquors_, such as brandy, whisky, rum, and
gin, which contain from thirty to sixty-five per cent of alcohol.
Alcoholic beverages all contain constituents other than alcohol,
these varying with the materials from which they are made and with
the processes of manufacture. The distilled liquors are so called
from the fact that their alcohol has been separated from the
fermenting substances by distillation.
136 Duncan, _The Chemistry of Commerce_.
137 Alcohol is "denatured" by adding substances to it such as wood
alcohol, which render its use as a beverage impossible.
138 The tobacco plant, _Nicotiana tobacum_, is a native of America, and
the use of tobacco began with the American Indians. It was taken
back to Europe by the early explorers, Sir Walter Raleigh being
credited with introducing it to the nobility of England.
139 Most headaches are the result either of eye strain or of digestive
disturbances, such as indigestion and constipation, and are to be
relieved through the work of the oculist or through attention to the
hygiene of the digestive system.