Pecking instinct of chicks, 256 Pecten, 118 Pedigrees, of genera, 84 Pelopæus, 260 Penguin, wings of, 287 Pentacrinus, 119 Perception, 208, 212, 253; an act of, 208; of personality, not personality, 212; sensory, 253 Percepts, objective, 235; sensory, 219 Periodicity, 56; of elements, 56; families of elements, 56 Peri Psyches, Aristotle’s, 196, 197, 215 Perissodactyla, 78 Permian, 104, 118 Persistence, 116, 119, 123; cannot be subsumed under same principles as transmutations, 123; its significance intensified by current theories, 123; of types, 119; of unchanged types, 116 Persistent types, generic and specific, 123 Personal identity, sense of, 212 Personality, 205, 211, 212, 238; a unitary and uniform reality, 212; alternating, 211; based on unchanging principle, 212; perception of, 212 Pessimism, 355, 357 Petit-Puymoyen, industry of, 331 Phæophytin, 147 Pharyngeal arches and clefts, 278, 279 Phase, reversal of, 168, 169 Phenomena, 208, 209; phenomenalists’ substantialization of, 209 Phenomenalism, 207, 208, 211, 212; a purely academic philosophy, 211; identifies mind with “thought stream,” 212 Phenomenalistic school, 206 Phenomenalists, 203, 205, 206, 207; inconsistently admit of physical phenomena while denying subject of psychic phenomena, 206, 207 Phenotype, 5, 19, 25, 27, 41, 43, 68, 123 Philology, 339; proves primitive man to have been civilized, not barbaric, 339 Philosophers, 220 Philosophy, 189, 190, 195; in rôle of critic, 189; in rôle of sycophant, 190; materialistic, 195; relation to science, 189 Phonetic elements, 246 Photosynthesis, 146 Phycocyanin, 149 Phylogeny, 39, 80, 122, 275, 276, 284, 285, 308; human, 285, 308; palæontological, 115 Phylum, 37, 38, 69, 116 Physical impressions, 213 Physical science, 352, 354 Physicochemical action, reducible to interaction between unequally energized masses and particles, 175 Physicochemical forces, executive factors in vital operations, 201 Physiology, 350 Phytol, 147 Picotee sweet pea, 19 Piltdown skull, 320 Pineal eye, 292 Pineal gland, 292, 293, 295; not functionless, 293 Pioneer colonies, 110 Pithecanthropus, distinctly simian, 342 Pithecanthropus erectus, 309, 313-318, 342; cranial capacity of, 314; a giant ape, 315; existing casts inaccurate, 318 Pituitary body, 292, 293 Pituitrin, 294 Placenta, 276 Planarian, 278 Planetesimal, hypothesis, 181 Plantigrade, 272 Plastids, 139, 141 Platycrinidae, 92 Platyrhine monkeys, 287 Pleistocene, 78, 100, 104, 313, 319, 320, 325; Lower, 313, 320; Middle, 319