Animal Life and Intelligence

by C. Lloyd Morgan

I

• Ichneumon fly, instinct of, [430]
• Ichthyosaurus, pineal eye of, [288]
• Icteridæ, [454]
• Idea of an object, [313]
• Ideas, conceptual, their environment, [485];
  • the law of their evolution, [486]
• Idealism, [474]
• Ignorance of animals, [333]
• Image, inverted in retina, [311]
• Imagination, constructive, [325]
• Imitation as a factor in habit or instinct, [443], [453]
• Immortality of protozoa, [12]
• Incongruity, elimination by, [486]
• Increase, law of, [58]
• Incubation, instinct of, [434]
• Individuality, a tendency to differentiation, [183]
• Inference, conscious and unconscious, [328];
  • in animals, [361]
• Infertility of isolated forms, [108]
• Infusoria, reproduction in, [39]
• Inheritance, exclusive, a means of isolation, [104];
  • of variations, [223];
  • of acquired habits, [435];
  • of acquired increments of intellectual faculty, [497]
• Inhibition, [385];
  • as a condition of volition, [459]
• Innate capacity, [422];
  • its importance, [429]
• Insects, tracheal respiration of, [3], [24];
  • wingless, of Madeira, [81];
  • of Kerguelen Island, [81];
  • mimicry and protective resemblance in, [85], [88];
  • segregation by colour, [101];
  • antennæ of, [178];
  • mouth-organs of, [179];
  • and the evolution of flowers, [206];
  • sense of touch in, [248];
  • taste in, [253];
  • smell in, [257];
  • hearing in, [266];
  • sight in, [288];
  • perceptual powers of, [357];
  • neuter, [440]
• Instinct and available advantage, [211];
  • consideration of, [415];
  • perfect, imperfect, and incomplete, [422];
  • deferred, [423];
  • blind prevision in, [429];
  • gratification in performance of, [430];
  • consciousness and, [432];
  • primary and secondary, [434];
  • three factors in the origin of, [447];
  • as influenced by intelligence, [452];
  • by imitation, [453];
  • by education, [455];
  • as distinguished from intelligence, [457]
• Instinctive emotion, [390], [395]
• Integration and differentiation, [183]
• Intellectual development, [486]
• Intelligence involved in selection, [95];
  • distinguished from reason, [330], [365];
  • lapsed, [435]
  • involved in instinct, [440];
  • as influencing instinct, [452];
  • criteria of, [456]
• Interbreeding and intercrossing, [97]
• Interneural evolution, [490]
• Interpretations of nature, genera and species of, [492]
• Isle of Man, tortoiseshell butterfly of, [81]
• Isolates, [322], [364]
• Isolation, organic, or segregation, [99];
  • mental, or abstraction, [322]