Impregnation, period of, influence of, upon sex.
Improvement, progressive, man alone supposed to be capable of.
Incisor teeth, knocked out or filed by some savages.
Increase, rate of; necessity of checks in.
Indecency, hatred of, a modern virtue.
India, difficulty of distinguishing the native races of; Cyprinidae of; colour of the beard in races of men of.
Indian, North American, honoured for scalping a man of another tribe.
Individuality, in animals.
Indolence of man, when free from a struggle for existence.
Indopicus carlotta, colours of the sexes of.
Infanticide, prevalence of; supposed cause of; prevalence and causes of.
Inferiority, supposed physical, of man.
Inflammation of the bowels, occurrence of, in Cebus Azarae.
Inheritance, of long and short sight; of effects of use of vocal and mental organs; of moral tendencies; laws of; sexual; sexually limited.
Inquisition, influence of the.
Insanity, hereditary.
insect, fossil, from the Devonian.
Insectivora, absence of secondary sexual characters in.
Insects, relative size of the cerebral ganglia in; male, appearance of, before the females; pursuit of female, by the males; period of development of sexual characters in; secondary sexual characters of; kept in cages; stridulation.
Insessores, vocal organs of.
Instep, depth of, in soldiers and sailors.
Instinct and intelligence.
Instinct, migratory, vanquishing the maternal.
Instinctive actions, the result of inheritance.
Instinctive impulses, difference of the force; and moral impulses, alliance of.
Instincts, complex origin of, through natural selection; possible origin of some; acquired, of domestic animals; variability of the force of; difference of force between the social and other; utilised for new purposes.
Instrumental music of birds.
Intellect, influence of, in natural selection in civilised society.
Intellectual faculties, their influence on natural selection in man; probably perfected through natural selection.
Intelligence, Mr. H. Spencer on the dawn of.
Intemperance, no reproach among savages; its destructiveness.
Intoxication in monkeys.
Iphias glaucippe.
Iris, sexual difference in the colour of the, in birds.
Ischio-pubic muscle.
Ithaginis cruentus, number of spurs in.
Iulus, tarsal suckers of the males of.
Jackals learning from dogs to bark.
Jack-snipe, coloration of the.
Jacquinot, on the number of species of man.
Jaeger, Dr., length of bones increased from carrying weights; on the difficulty of approaching herds of wild animals; male Silver-pheasant, rejected when his plumage was spoilt.
Jaguars, black.
Janson, E.W., on the proportions of the sexes in Tomicus villosus; on stridulant beetles.
Japan, encouragement of licentiousness in.
Japanese, general beardlessness of the; aversion of the, to whiskers.
Jardine, Sir W., on the Argus pheasant.
Jarrold, Dr., on modifications of the skull induced by unnatural position.
Jarves, Mr., on infanticide in the Sandwich Islands.
Javans, relative height of the sexes of; notions of female beauty.
Jaw, influence of the muscles of the, upon the physiognomy of the apes.
Jaws, smaller proportionately to the extremities; influence of food upon the size of; diminution of, in man; in man, reduced by correlation.
Jay, young of the; Canada, young of the.
Jays, new mates found by; distinguishing persons.
Jeffreys, J. Gwyn, on the form of the shell in the sexes of the Gasteropoda; on the influence of light upon the colours of shells.
Jelly-fish, bright colours of some.
Jenner, Dr., on the voice of the rook; on the finding of new mates by magpies; on retardation of the generative functions in birds.
Jenyns, L., on the desertion of their young by swallows; on male birds singing after the proper season.
Jerdon, Dr., on birds dreaming; on the pugnacity of the male bulbul; on the pugnacity of the male Ortygornis gularis; on the spurs of Galloperdix; on the habits of Lobivanellus; on the spoonbill; on the drumming of the Kalij-pheasant; on Indian bustards; on Otis bengalensis; on the ear-tufts of Sypheotides auritus; on the double moults of certain birds; on the moulting of the honeysuckers; on the moulting of bustards, plovers, and drongos; on the spring change of colour in some finches; on display in male birds; on the display of the under-tail coverts by the male bulbul; on the Indian honey-buzzard; on sexual differences in the colour of the eyes of hornbills; on the markings of the Tragopan pheasant; on the nidification of the Orioles; on the nidification of the hornbills; on the Sultan yellow-tit; on Palaeornis javanicus; on the immature plumage of birds; on representative species of birds; on the habits of Turnix; on the continued increase of beauty of the peacock; on coloration in the genus Palaeornis.