The Prolongation of Life: Optimistic Studies is a public-domain classic of science by Elie Metchnikoff.
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THE INVESTIGATION OF OLD AGE
THE PROBLEMS OF SENILITY
Treatment of old people in uncivilised countries.—Assassination of old people in civilised countries.—Suicide of old people.—Public assistance in old age.—Centenarians.—Mme. Robineau, a lady of 106 years of age.—Principal characters of old age.—Examples of old mammals.—Old birds and tortoises.—Hypothesis of senile degeneration in the lower animals 1
THEORIES OF THE CAUSATION OF SENILITY
Hypothesis of the causation of senility.—Senility cannot be attributed to the cessation of the power of reproduction of the cells of the body.—Growth of the hair and the nails in old age.—Inner mechanism of the senescence of the tissues.—Notwithstanding the criticisms of M. Marinesco, the neuronophags are true phagocytes.—The whitening of hair, and the destruction of nerve cells as arguments against a theory of old age based on the failure of the reproductive powers of the cells 15
III
MECHANISM OF SENILITY
Action of the macrophags in destroying the higher cells.—Senile degeneration of the muscular fibres.—Atrophy of the skeleton.—Atheroma and arterial sclerosis.—Theory that Old Age is due to alteration in the vascular glands.—Organic tissues that resist phagocytosis. 25
LONGEVITY IN THE ANIMAL KINGDOM
THEORIES OF LONGEVITY
Relation between longevity and size.—Longevity and the period of growth.—Longevity and the doubling in weight after birth.—Longevity and rate of reproduction.—Probable relations between longevity and the nature of the food 39
LONGEVITY IN THE ANIMAL KINGDOM
Longevity in the lower animals.—Instances of long life in sea-anemones and other vertebrates.—Duration of life of insects.—Duration of life of “cold-blooded” vertebrates.—Duration of life of birds.—Duration of life of mammals.—Inequality of the duration of life in males and females.—Relations between longevity and fertility of the organism 47
III
THE DIGESTIVE SYSTEM AND SENILITY
Relations between longevity and the structure of the digestive system.—The cæca in birds.—The large intestine of mammals.—Function of the large intestine.—The intestinal microbes and their agency in producing auto-intoxication and auto-infection in the organism.—Passage of microbes through the intestinal wall 59
MICROBES AS THE CAUSE OF SENILITY
Relations between longevity and the intestinal flora.—Ruminants.—The horse.—Intestinal flora of birds.—Intestinal flora of cursorial birds.—Duration of life in cursorial birds.—Flying mammals.—Intestinal flora and longevity of bats.—Some exceptions to the rule.—Resistance of the lower vertebrates to certain intestinal microbes 73
DURATION OF HUMAN LIFE
Longevity of man.—Theory of Ebstein on the normal duration of human life.—Instances of human longevity.—Circumstances which may explain the long duration of human life 84
INVESTIGATIONS ON NATURAL DEATH
NATURAL DEATH AMONGST PLANTS
Theory of the immortality of unicellular organisms.—Examples of very old trees.—Examples of short-lived plants.—Prolongation of the life of some plants.—Theory of the natural death of plants by exhaustion.—Death of plants from auto-intoxication 94
NATURAL DEATH IN THE ANIMAL WORLD
Different origins of death in animals.—Examples of natural death associated with violent acts.—Examples of natural death in animals without digestive organs.—Natural death in the two sexes.—Hypothesis as to the cause of natural death in animals 109
III
NATURAL DEATH AMONGST HUMAN BEINGS
Natural death in the aged.—Analogy of natural death and sleep.—Theories of sleep.—Ponogenes.—The instinct of sleep.—The instinct of natural death.—Replies to critics.—Agreeable sensation at the approach of death 119
SHOULD WE TRY TO PROLONG HUMAN LIFE?
THE BENEFIT TO HUMANITY
Complaints of the shortness of our life.—Theory of “medical selection” as a cause of degeneration of the race.—Utility of prolonging human life 132
SUGGESTIONS FOR THE PROLONGATION OF LIFE
Ancient methods of prolonging human life.—Gerokomy.—The “immortality draught” of the Taoists.—Brown-Séquard’s method.—The spermine of Poehl.—Dr. Weber’s precepts.—Increased duration of life in historical times.—Hygienic maxims.—Decrease in cutaneous cancer 136
III
DISEASES THAT SHORTEN LIFE
Measures against infectious diseases as aiding in the prolongation of life.—Prevention of syphilis.—Attempts to prepare serums which could strengthen the higher elements of the organism 145
INTESTINAL PUTREFACTION SHORTENS LIFE
Uselessness of the large intestine in man.—Case of a woman whose large intestine was inactive for six months.—Another case where the greater part of the large intestine was completely shut off.—Attempts to disinfect the contents of the large intestine.—Prolonged mastication as a means of preventing intestinal putrefaction 151
LACTIC ACID AS INHIBITING INTESTINAL PUTREFACTION
The development of the intestinal flora in man.—Harmlessness of sterilised food.—Means of preventing the putrefaction of food.—Lactic fermentation and its anti-putrescent action.—Experiments on man and mice.—Longevity in races which used soured milk.—Comparative study of different soured milks.—Properties of the Bulgarian Bacillus.—Means of preventing intestinal putrefaction with the help of microbes 161
PSYCHICAL RUDIMENTS IN MAN
RUDIMENTARY ORGANS IN MAN
Reply to critics who deny the simian origin of man.—Actual existence of rudimentary organs.—Reductions in the structure of the organs of sense in man.—Atrophy of Jacobson’s organ and of the Harderian gland in the human race 184
HUMAN TRAITS OF CHARACTER INHERITED FROM APES
The mental character of anthropoid apes.—Their muscular strength.—Their expression of fear.—The awakening of latent instincts of man under the influence of fear 191
III
SOMNAMBULISM AND HYSTERIA AS MENTAL RELICS
Fear as the primary cause of hysteria.—Natural somnambulism.—Doubling of personality.—Some examples of somnambulists.—Analogy between somnambulism and the life of anthropoid apes.—The psychology of crowds.—Importance of the investigation of hysteria for the problem of the origin of man 200
SOME POINTS IN THE HISTORY OF SOCIAL ANIMALS
THE INDIVIDUAL AND THE RACE
Problem of the species in the human race.—Loss of individuality in the associations of lower animals.—Myxomycetes and Siphonophora.—Individuality in Ascidians.—Progress in the development of the individual living in a society 212
INSECT SOCIETIES
Social life of insects.—Development and preservation of individuality in colonies of insects.—Division of labour and sacrifice of individuality in some insects 220
III
SOCIETY AND THE INDIVIDUAL IN THE HUMAN RACE
Human societies.—Differentiation in the human race.—Learned women.—Habits of a bee, Halictus quadricinctus.—Collectivist theories.—Criticisms by Herbert Spencer and Nietzsche.—Progress of individuality in the societies of higher beings 223
PESSIMISM AND OPTIMISM
PREVALENCE OF PESSIMISM
Oriental origin of pessimism.—Pessimistic poets.—Byron.—Leopardi.—Poushkin.—Lermontoff.—Pessimism and suicide 233
ANALYSIS OF PESSIMISM
Attempts to assign reasons for the pessimistic conception of life.—Views of E. von Hartmann.—Analysis of Kowalevsky’s work on the psychology of pessimism 239
III
PESSIMISM IN ITS RELATION TO HEALTH AND AGE
Relation between pessimism and the state of the health.—History of a man of science who was pessimistic when young and who became an optimist in old age.—Optimism of Schopenhauer when old.—Development of the sense of life.—Development of the senses in blind people.—The sense of obstacles 247
GOETHE AND FAUST
GOETHE’S YOUTH
Goethe’s youth.—Pessimism of youth.—Werther.—Tendency to suicide.—Work and love.—Goethe’s conception of life in his maturity 261
GOETHE AND OPTIMISM
Goethe’s optimistic period.—His mode of life in that period.—Influence of love in artistic production.—Inclinations towards the arts must be regarded as secondary sexual characters.—Senile love of Goethe.—Relation between genius and the sexual activities 270
III
GOETHE’S OLD AGE
Old age of Goethe.—Physical and intellectual vigour of the old man.—Optimistic conception of life.—Happiness in life in his last period 279
GOETHE AND “FAUST”
Faust the biography of Goethe.—The three monologues in the first Part.—Faust’s pessimism.—The brain-fatigue which finds a remedy in love.—The romance with Marguerite and its unhappy ending 283
THE OLD AGE OF FAUST
The second Part of Faust is in the main a description of senile love.—Amorous passion of the old man.—Humble attitude of the old Faust.—Platonic love for Helena.—The old Faust’s conception of life.—His optimism.—The general idea of the play 290
SCIENCE AND MORALITY
UTILITARIAN AND INTUITIVE MORALITY
Difficulty of the problem of morality.—Vivisection and anti-vivisection.—Enquiry into the possibility of rational morality.—Utilitarian and intuitive theories of morality.—Insufficiency of these 301
MORALITY AND HUMAN NATURE
Attempts to found morality on the laws of human nature.—Kant’s theory of moral obligation.—Some criticisms of the Kantian theory.—Moral conduct must be guided by reason 309
III
INDIVIDUALISM
Individual morality.—History of two brothers brought up in the same circumstances, but whose conduct was quite different.—Late development of the sense of life.—Evolution of sympathy.—The sphere of egoism in moral conduct.—Christian morality.—Morality of Herbert Spencer.—Danger of exalted altruism 316
ORTHOBIOSIS
Human nature must be modified according to an ideal.—Comparison with the modification of the constitution of plants and of animals.—Schlanstedt rye.—Burbank’s plants.—The ideal of orthobiosis.—The immorality of ignorance.—The place of hygiene in the social life.—The place of altruism in moral conduct.—The freedom of the theory of orthobiosis from metaphysics 325
THE PROLONGATION OF LIFE
THE INVESTIGATION OF OLD AGE
THE PROBLEMS OF SENILITY
Treatment of old people in uncivilised countries—Assassination of old people in civilised countries—Suicide of old people—Public assistance in old age—Centenarians—Mme. Robineau, a lady of 106 years of age—Principal characters of old age—Examples of old mammals—Old birds and tortoises—Hypothesis of senile degeneration in the lower animals
In the “Nature of Man” I laid down the outlines of a theory of the actual changes which take place during the senescence of our body. These ideas, on the one hand, have raised certain difficulties, and, on the other, have led to new investigations. As the study of old age is of great theoretical importance, and naturally is of practical value, I think that it is useful to pursue the subject still further.
Although there exist races which solve the difficulty of old age by the simple means of destroying aged people, the problem in civilised countries is complicated by our more refined feelings and by considerations of a general nature.
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