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

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

Action of the macrophags in destroying the higher cells.—Senile degeneration of the muscular fibres.—Atrophy of the xiv skeleton.—Atheroma and arterial sclerosis.—Theory that Old Age is due to alteration in the vascular glands.—Organic tissues that resist phagocytosis.

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

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

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

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

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

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

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

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

Complaints of the shortness of our life.—Theory of “medical selection” as a cause of degeneration of the race.—Utility of prolonging human 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

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

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

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

Reply to critics who deny the simian origin of man.—Actual xviiexistence 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

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

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

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

Social life of insects.—Development and preservation of individuality in colonies of insects.—Division of labour and sacrifice of individuality in some insects

Human societies.—Differentiation in the human race.—Learned women.—Habits of a bee, Halictus quadricinctus.—Collectivist theories.—Criticisms by Herbert Spencer and xviii Nietzsche.—Progress of individuality in the societies of higher beings

Oriental origin of pessimism.—Pessimistic poets.—Byron.—Leopardi.—Poushkin.—Lermontoff.—Pessimism and suicide

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

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

Goethe’s youth.—Pessimism of youth.—Werther.—Tendency to suicide.—Work and love.—Goethe’s conception of life in his maturity

Goethe’s optimistic period.—His mode of life in that period.—Influence of love in artistic production.—Inclinations xixtowards the arts must be regarded as secondary sexual characters.—Senile love of Goethe.—Relation between genius and the sexual activities

Old age of Goethe.—Physical and intellectual vigour of the old man.—Optimistic conception of life.—Happiness in life in his last period

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

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

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

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

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

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