The organised world before the appearance of man on the earth—Absence of a law of universal progress—Fertilisation of vanilla—The part played by insects in the fertilisation of orchids—Mechanism by which insects carry the pollen of orchids—Habits of fossorial wasps—Harmonies in nature—Useless organs—Rudiments of the pollinia of orchids—Disharmonies in nature—Unadapted insects—Aberration of instincts—Perversion of sexual instinct—Attraction of insects by light—Luminous insects—Law of natural selection—Happiness and unhappiness in the organised world CHAPTER III SIMIAN ORIGIN OF MAN 40 Relationship of the human species with anthropoid apes—Analogies in the dentition, in the organisation of the limbs and of the brain—Resemblance of the vermiform appendage of man and anthropoids—Analogy between the placenta and fœtus of man and anthropoid apes—Blood relationship of man and monkeys shown by serums and precipitates—Transmutation of species—Sudden transition from monkey to man—J. Inaudi, the calculator, as an example of the sudden appearance of characters in the human species—Rudimentary organs in man—Proportion of progressive and retrogressive organs in the organisation of man CHAPTER IV DISHARMONIES IN THE ORGANISATION OF THE DIGESTIVE SYSTEM OF MAN 61 Perfection of the human form—The covering of hair—The dentition in general, and the wisdom teeth—The vermiform appendage—Appendicitis and its gravity—Uselessness of the cæcum and of the large intestine—Instance of a woman without a large intestine—Ancestral history of this portion of the digestive tract—Injurious effect of the microbes of the large intestine—Frequency of cancer of the large intestine and of the stomach—Limited usefulness of the stomach—The instinct of choice of food—Futility of this instinct in man CHAPTER V DISHARMONIES IN THE ORGANISATION AND ACTIVITIES OF THE REPRODUCTIVE APPARATUS—DISHARMONIES IN THE FAMILY AND SOCIAL INSTINCTS 78 I Remarks on the disharmonies in the human organs of sense and perception—Rudimentary parts of the reproductive apparatus—Origin and function of the hymen II Evolution and significance of the menstrual flow in women—Precocious marriage amongst primitive and uncivilised races—Disharmony between age of puberty and age of nubility—Age of marriage—Examples of disharmony in the development of the reproductive function III