Physiological classification, and ecological succession, 21 in ecology, 101, 133, 134 Physiological conditions, 92, 93 Physiological life histories of plants, 17 Physiological problems and dynamic theory, 97 Physiological responses, distribution due to, 101, 112, 136 of fish, 112 Physiological states and rheotaxis in Isopoda, 106 Physiology, comparative, 95 general, 95 of organisms, 96 of organs, 96 of reproduction, 100 Phytogeographical nomenclature, 22, 60 Pigeon, common, 117 homing, 113 passenger, 117 Pigeons, emotion in, 110 methods of homing, 113 voices as means of social control, 106, 134 Planarians, behavior, 120 distribution locally, 120 reactions of fresh-water, 116 reactions to light, 105 Plane table manual, 64 Plankton, 60, 148 ecological study, 140 investigations of Danish lakes, 140 of Illinois river, 147 of Shawnee Cave, ecological study, 145 organisms, 50 Plant animals, 128 Plant ecology, 59 bibliography, 89 general principles, 88, 89 Plant formations, stable and migratory, 88 Plant galls, 143 animals in relation to, 141 biology and causes of European, 143 Plant societies, relation to evaporation, 64, 90 relation to humidity, 90 study of Chicago, 88 Plant succession, 90 relation to distribution of tiger beetles, 90 Plants, and ants, 126, 127 and snails, 125 forming animal habitats, 89 influence upon insects, 135 life histories, physiological, 17 seasonal succession, 140 variation, 96 Play of animals, 112 _Plethodon cinereus erythronotus_, habits, 117 larval state, 117 Poduridæ, behavior and habitat, 136 movements, 136 Poisons, physiological effect of certain, 99 Pollination, animals in relation to, 141 Pollination of flowers, animals in relation, 141, 142 Pollination of Yucca, 142 Pond, fauna, 148 fish, ecological succession, 133 habitat, 148 Isopods, 106 Pond snail, behavior, 120 Pond, solution, 148 Ponds, seasonal succession in old forest, 140 Porcupine mountains, 91 Postglacial dispersal of biota, 91 Potassium cyanide, effects on sea-urchin, 99 Potato beetles, _see Leptinotarsa_ Predaceous beetles, food, 126, 130 Preservation of specimens, 49, 50 Preserves, natural, 34, 38 Principles, value of general, 41 Process, animal behavior as a, 102 Process method, application, 86 of investigation, 56 Process of adjustment, 30, 31 in organisms, 122 Process of response, 4 Process standpoint, 91, 101 applied to vegetation, 88 Processes, geologic, 86 of behavior, 93 of development, 93 of growth, 93 of metabolism, 93 of research, 55 regulatory character of physico-chemical and physiological, 85 standpoint, 80, 81, 82 Production, conditions of, in the sea, 87