Disease and Its Causes

CHAPTER I

DEFINITION OF DISEASE.--CHARACTERISTICS OF LIVING MATTER.--CELLS AS THE LIVING UNITS.--AMOEBA AS TYPE OF A UNICELLULAR ANIMAL.--THE RELATION OF LIVING MATTER TO ENVIRONMENT.--CAPACITY OF ADAPTATION TO ENVIRONMENT SHOWN BY LIVING MATTER.--INDIVIDUALITY OF LIVING MATTER.--THE CAUSES OF DISEASE EXTRINSIC.--THE RELATION OF THE HUMAN BODY TO THE ENVIRONMENT.--THE SURFACES OF THE BODY.--THE INCREASE OF SURFACE BY GLAND FORMATION.--THE REAL INTERIOR OF THE BODY REPRESENTED BY THE VARIOUS STRUCTURES PLACED BETWEEN THE SURFACES.--THE FLUIDS OF THE BODY.--THE NERVOUS SYSTEM.--THE HEART AND BLOOD-VESSELS.--THE CELLS OF THE BLOOD.--THE DUCTLESS GLANDS 9

CHAPTER II. No Sharp Line of Demarcation Between Health and Disease.--the

NO SHARP LINE OF DEMARCATION BETWEEN HEALTH AND DISEASE.--THE FUNCTIONAL NUTRITIVE AND FORMATIVE ACTIVITIES OF CELLS.--DESTRUCTION AND REPAIR CONSTANT PROCESSES IN LIVING MATTER.--INJURIES TO THE BODY.--THE EFFECT OF HEAT.--THE ACTION OF POISONS.--THE LESIONS OF DISEASE.--REPAIR.--THE LAWS GOVERNING REPAIR.--RELATION OF REPAIR TO COMPLEXITY OF STRUCTURE AND AGE.--THE RESERVE FORCE OF THE BODY.--COMPENSATORY PROCESSES IN THE BODY.--OLD AGE.--THE DIMINUTION OF RESISTANCE TO THE EFFECTS OF THE ENVIRONMENT A PROMINENT FACTOR IN OLD AGE.--DEATH.--HOW BROUGHT ABOUT.--CHANGES IN THE BODY AFTER DEATH.--THE RECOGNITION OF DEATH 40

CHAPTER III

THE GROWTH OF THE BODY.--GROWTH MORE RAPID IN EMBRYONIC PERIOD.--THE COÖRDINATION AND REGULATION OF GROWTH.--TUMORS.--THE GROWTH OF TUMORS COMPARED WITH NORMAL GROWTH.--SIZE. SHAPE AND STRUCTURE OF TUMORS.--THE GROWTH CAPACITY OF TUMORS AS SHOWN BY THE INOCULATION OF TUMORS OF MICE.--BENIGN AND MALIGNANT TUMORS.--EFFECT OF INHERITANCE.--ARE TUMORS BECOMING MORE FREQUENT?--THE EFFECT PRODUCED BY A TUMOR ON THE INDIVIDUAL WHO BEARS IT.--RELATION OF TUMORS TO AGE AND SEX.--THEORIES AS TO THE CAUSE OF TUMORS.--THE PARASITIC THEORY.--THE TRAUMATIC THEORY.--THE EMBRYONIC THEORY.--THE IMPORTANCE OF THE EARLY RECOGNITION AND REMOVAL OF TUMORS 62

CHAPTER IV

THE REACTIONS OF THE TISSUES OF THE BODY TO INJURIES.--INFLAMMATION.-- THE CHANGES IN THE BLOOD IN THIS.--THE LMIGRATION OF THE CORPUSCLES OF THE BLOOD.--THE EVIDENT CHANGES IN THE INJURED PART AND THE MANNER IN WHICH THESE ARE PRODUCED.--HEAT REDNESS SWELLING AND PAIN.--THE PRODUCTION OF BLISTERS BY SUNBURN.--THE CHANGES IN THE CELLS OF AN INJURED PART.--THE CELLS WHICH MIGRATE FROM THE BLOOD VESSELS ACT AS PHAGOCYTES.--THE MACROPHAGES.--THE MICROPHAGES.--CHEMOTROPISM.--THE HEALING OF INFLAMMATION.--THE REMOVAL OF THE CAUSE.--CELL REPAIR AND NEW FORMATION.--NEW FORMATION OF BLOOD VESSELS.--ACUTE AND CHRONIC INFLAMMATION.--THE APPARENTLY PURPOSEFUL CHARACTER OF THE CHANGES IN INFLAMMATION 79

CHAPTER V. Infectious Diseases.--the Historical Importance of Epidemics of

INFECTIOUS DISEASES.--THE HISTORICAL IMPORTANCE OF EPIDEMICS OF DISEASE.--THE LOSSES IN BATTLE CONTRASTED WITH THE LOSSES IN ARMIES PRODUCED BY INFECTIOUS DISEASES.--THE DEVELOPMENT OF KNOWLEDGE OF EPIDEMICS.--THE VIEWS OF HIPPOCRATES AND ARISTOTLE.--SPORADIC AND EPIDEMIC DISEASES.--THE THEORY OF THE EPIDEMIC CONSTITUTION.--THEORY THAT THE CONTAGIOUS MATERIAL IS LIVING.--THE DISCOVERY OF BACTERIA BY LOEWENHOECK IN 1675.--THE RELATION OF CONTAGION TO THE THEORY OF SPONTANEOUS GENERATION.--NEEDHAM AND SPALLANZANI.--THE DISCOVERY OF THE COMPOUND MICROSCOPE IN 1605.--THE PROOF THAT A LIVING ORGANISM IS THE CAUSE OF A DISEASE.--ANTHRAX.--THE DISCOVERY OF THE ANTHRAX BACILLUS IN 1851.--THE CULTIVATION OF THE BACILLUS BY KOCH.--THE MODE OF INFECTION.--THE WORK OF PASTEUR ON ANTHRAX.--THE IMPORTANCE OF THE DISEASE 97

CHAPTER VI

CLASSIFICATION OF THE ORGANISMS WHICH CAUSE DISEASE.--BACTERIA SIZE SHAPE STRUCTURE CAPACITY FOR GROWTH MULTIPLICATION AND SPORE INFORMATION.--THE ARTIFICIAL CULTIVATION OF BACTERIA.--THE IMPORTANCE OF BACTERIA IN NATURE.--VARIATIONS IN BACTERIA.--SAPROPHYTIC AND PARASITIC FORMS.--PROTOZOA.--STRUCTURE MORE COMPLICATED THAN THAT OF BACTERIA.--DISTRIBUTION IN NATURE.--GROWTH AND MULTIPLICATION.--CONJUGATION AND SEXUAL REPRODUCTION.--SPORE FORMATION.--THE NECESSITY FOR A FLUID ENVIRONMENT.--THE FOOD OF PROTOZOA.--PARASITISM.--THE ULTRA MICROSCOPIC OR FILTERABLE ORGANISMS.--THE LIMITATION OF THE MICROSCOPIC.--PORCELAIN FILTERS TO SEPARATE ORGANISMS FROM A FLUID.--FOOT AND MOUTH DISEASE PRODUCED BY AN ULTRA MICROSCOPIC ORGANISM.--OTHER DISEASES SO PRODUCED.--DO NEW DISEASES APPEAR? 116

CHAPTER VII. The Nature of Infection.--the Invasion of the Body From Its

THE NATURE OF INFECTION.--THE INVASION OF THE BODY FROM ITS SURFACES.--THE PROTECTION OF THESE SURFACES.--CAN BACTERIA PASS THROUGH AN UNINJURED SURFACE?.--INFECTION FROM WOUNDS.--THE WOUNDS IN MODERN WARFARE LESS PRONE TO INFECTION.--THE RELATION OF TETANUS TO WOUNDS CAUSED BY THE TOY PISTOL.--THE PRIMARY FOCUS OR ATRIUM OF INFECTION.--THE DISSEMINATION OF BACTERIA IN THE BODY.--THE DIFFERENT DEGREES OF RESISTANCE TO BACTERIA SHOWN BY THE VARIOUS ORGANS.--MODE OF ACTION OF BACTERIA.--TOXIN PRODUCTION.--THE RESISTANCE OF THE BODY TO BACTERIA.--CONFLICT BETWEEN PARASITE AND HOST.--ON BOTH SIDES MEANS OF OFFENSE AND DEFENSE.--PHAGOCYTOSIS.--THE DESTRUCTION OF BACTERIA BY THE BLOOD.--THE TOXIC BACTERIAL DISEASES.--TOXIN AND ANTITOXIN.--IMMUNITY.-- THE THEORY OF EHRLICH 135

CHAPTER VIII

SECONDARY TERMINAL AND MIXED INFECTIONS.--THE EXTENSION OF INFECTION IN THE INDIVIDUAL.--TUBERCULOSIS.--THE TUBERCLE BACILLUS.--FREQUENCY OF THE DISEASE.--THE PRIMARY FOCI.--THE EXTENSION OF BACILLI.--THE DISCHARGE OF BACILLI FROM THE BODY.--INFLUENCE OF THE SEAT OF DISEASE ON THE DISCHARGE OF BACILLI.--THE INTESTINAL DISEASES.--MODES OF INFECTION.--INFECTION BY SPUTUM SPRAY.--INFECTION OF WATER SUPPLIES.--EXTENSION OF INFECTION BY INSECTS.--TRYPANASOME DISEASES.--SLEEPING SICKNESS.--MALARIA.--THE PART PLAYED BY MOSQUITOES.--PARASITISM IN THE MOSQUITO.--INFECTION AS INFLUENCED BY HABITS AND CUSTOMS.--HOOKWORM DISEASE.--INTERRELATION BETWEEN HUMAN AND ANIMAL DISEASES.--PLAGUE.--PART PLAYED RATS IN TRANSMISSION.--THE PRESENT EPIDEMIC OF PLAGUE 159

CHAPTER IX

DISEASE CARRIERS.--THE RELATION BETWEEN SPORADIC CASES OF INFECTIOUS DISEASE AND EPIDEMICS.--SMALLPOX.--CEREBROSPINAL MENINGITIS.--POLYOMYELITIS.--VARIATION IN THE SUSCEPTIBILITY OF INDIVIDUALS.--CONDITIONS WHICH MAY INFLUENCE SUSCEPTIBILITY.--RACIAL SUSCEPTIBILITY.--INFLUENCE OF AGE AND SEX.--OCCUPATION AND ENVIRONMENT.--THE AGE PERIOD OF INFECTIOUS DISEASES 185

CHAPTER X. Inheritance As a Factor in Disease.--the Process of Cell

INHERITANCE AS A FACTOR IN DISEASE.--THE PROCESS OF CELL MULTIPLICATION.--THE SEXUAL CELLS DIFFER FROM THE OTHER CELLS OF THE BODY.--INFECTION OF THE OVUM.--INTRAUTERINE INFECTION.--THE PLACENTA AS A BARRIER TO INFECTION.--VARIATIONS AND MUTATIONS.--THE INHERITANCE OF SUSCEPTIBILITY TO DISEASE.--THE INFLUENCE OF ALCOHOLISM IN THE PARENTS ON THE DESCENDANTS.--THE HEREDITY OF NERVOUS DISEASES.--TRANSMISSION OF DISEASE BY THE FEMALE ONLY.--HEMOPHILIA.--THE INHERITANCE OF MALFORMATIONS.--THE CAUSES OF MALFORMATIONS.--MATERNAL IMPRESSIONS HAVE NO INFLUENCE.--EUGENICS 197

CHAPTER XI

CHRONIC DISEASES.--DISEASE OF THE HEART AS AN EXAMPLE.--THE STRUCTURE AND FUNCTION OF THE HEART.--THE ACTION OF THE VALVES.--THE PRODUCTION OF HEART DISEASE BY INFECTION.--THE CONDITIONS PRODUCED IN THE VALVES.--THE MANNER IN WHICH DISEASE OF THE VALVES INTERFERES WITH THEIR FUNCTION,--THE COMPENSATION OF INJURY BY INCREASED ACTION OF HEART.--THE ENLARGEMENT OF THE HEART.--THE RESULT OF IMPERFECT WORK OF THE HEART.--VENOUS CONGESTION.--DROPSY.--CHRONIC DISEASE OF THE NERVOUS SYSTEM.--INSANITY.--RELATION BETWEEN INSANITY AND CRIMINALITY.--ALCOHOLISM AND SYPHILIS FREQUENT CAUSES OF INSANITY.--THE DIRECT AND INDIRECT CAUSES OF NERVOUS DISEASES.--THE RELATION BETWEEN SOCIAL LIFE AND NERVOUS DISEASES.--FUNCTIONAL AND ORGANIC DISEASE.--NEURASTHENIA 219

CHAPTER XII. The Rapid Development of Medicine in the Last Fifty Years.--the

THE RAPID DEVELOPMENT OF MEDICINE IN THE LAST FIFTY YEARS.--THE INFLUENCE OF DARWIN.--PREVENTIVE MEDICINE.--THE DISSEMINATION OF MEDICAL KNOWLEDGE.--THE DEVELOPMENT OF CONDITIONS IN RECENT YEARS WHICH ACT AS FACTORS OF DISEASE.--FACTORY LIFE.--URBAN LIFE.--THE INCREASE OF COMMUNICATION BETWEEN PEOPLES.--THE INTRODUCTION OF PLANT PARASITES.--THE INCREASE IN ASYLUM LIFE.--INFANT MORTALITY.--WEALTH AND POVERTY AS FACTORS IN DISEASE 241

GLOSSARY 250

INDEX 252

DISEASE AND ITS CAUSES

CHAPTER I

DEFINITION OF DISEASE.--CHARACTERISTICS OF LIVING MATTER.--CELLS AS THE LIVING UNITS.--AMOEBA AS TYPE OF A UNICELLULAR ANIMAL.--THE RELATION OF LIVING MATTER TO THE ENVIRONMENT.--CAPACITY OF ADAPTATION TO THE ENVIRONMENT SHOWN BY LIVING MATTER--INDIVIDUALITY OF LIVING MATTER.--THE CAUSES OF DISEASE.--EXTRINSIC.--THE RELATION OF THE HUMAN BODY TO THE ENVIRONMENT.--THE SURFACES OF THE BODY.--THE INCREASE OF SURFACE BY GLAND FORMATION.--THE REAL INTERIOR OF THE BODY REPRESENTED BY THE VARIOUS STRUCTURES PLACED BETWEEN THE SURFACES.--THE FLUIDS OF THE BODY.--THE NERVOUS SYSTEM.--THE HEART AND BLOOD-VESSELS.--THE CELLS OF THE BLOOD.--THE DUCTLESS GLANDS.

There is great difficulty, in the case of a subject so large and complex as is disease, in giving a definition which will be accurate and comprehensive. Disease may be defined as "A change produced in living things in consequence of which they are no longer in harmony with their environment." It is evident that this conception of disease is inseparable from the idea of life, since only a living thing can become diseased. In any dead body there has been a preëxisting disease or injury, and, in consequence of the change produced, that particular form of activity which constitutes life has ceased. Changes such as putrefaction take place in the dead body, but they are changes which would take place in any mass similarly constituted, and are not influenced by the fact that the mass was once living. Disease may also be thought of as the negation of the normal. There is, however, in living things no definite type for the normal. An ideal normal type may be constructed by taking the average of a large number of individuals; but any single individual of the group will, to a greater or less extent, depart from it. No two individuals have been found in whom all the Bertillon measurements agree. Disease has reference to the individual; conditions which in one individual would be regarded as disease need not be so regarded in another. Comparisons between health and disease, the normal and the abnormal, must be made not between the ideal normal and abnormal, but between what constitutes the normal or usual and the abnormal in a particular individual.

The conception of disease is so inseparably associated with that of life that a brief review of the structure and properties of living things is necessary for the comprehension of the definition which has been given. Living matter is subject to the laws which govern matter, and like matter of any other sort it is composed of atoms and molecules. There is no force inherent in living matter, no vital force independent of and differing from the cosmic forces; the energy which living matter gives off is counterbalanced by the energy which it receives. It undergoes constant change, and there is constant interchange with the environment. The molecules which compose it are constantly undergoing change in their number, kind and arrangement. Atom groups as decomposition products are constantly given off from it, and in return it receives from without other atom groups with which it regenerates its substance or increases in amount. All definitions of life convey this idea of activity. Herbert Spencer says, "Life is the continuous adjustment of internal relations to external conditions." The molecules of the substances forming the living material are large, complex and unstable, and as such they constantly tend to pass from the complex to the simple, from unstable to stable equilibrium. The elementary substances which form living material are known, but it has hitherto not been found possible artificially so to combine these substances that the resulting mass will exhibit those activities which we call the phenomena of life. The distinction between living and nonliving matter is manifest only when the sum of the activities of the living matter is considered; any single phenomenon of the living may appear also in the non-living material. Probably the most distinguishing criterion of living matter is found in its individuality, which undoubtedly depends upon differences in structure, whether physical or chemical, between the different units.

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