Instinct, determined by heredity, 206; of higher animals, 208; differs from intelligence in degree, 210.
Intelligence, 203; in mental life of communal insects, 207.
Invertebrates, lower animals devoid of backbone, 47; structural plan, 48; branches of, 49; groups, two layer animals, 50; hydra, sea-anemones, soft-polyps, 50; more complicated, 68; palæontological materials, 82; evolution of lowest members, 92.
Jaguar, 101.
Jastrow, 294.
Java, 173.
Jellyfish, 81.
Jordan, David Starr, 123.
Kangaroo, 42.
Keane, 185.