Part 78

Oak gall flies, and oak galls, 143

Oceanography, 21

Odonata, life histories, 76 transformations described, 72

Œcology, see Ecology

Oligochæta, 58

Ontario, Entomological Society of, index to thirty annual reports, 72

Optima, 98 development, 94 of Chætognatha, 115 physiological, 27 vital, 27, 94

Optimum, 30, 94 associational, 94 departure from, 98 vital conditions, 99 vital, in caves, 144

Orange, insects affecting the, 75

Orchestia palustris, habits and life history, 119

Orderly sequence, laws, 92, 93 of behavior, 113 of disturbances by man, 27 of environment, 79

Oregon beach, beetles of an, 149

Orientation among animals, 118

Origin of land animals, 148

Original conditions, 26, 27 of environment, 25, 26

Oriole, Baltimore, 117

Organ of taste, fish, 113

Organic parasitism, 126

Organism, ant colony as an, 131 as agent, 4

Organisms, behavior of lower, 96, 107 geometrical representations of the conflict between, 125 interactions, 49, 123 lower, behavior, 96, 107 physiology, 96 responses to light, 115

Organization of gull community, 106, 134

Organs, physiology, 96

Ornithological balance-wheel, 123

Orthoptera, biology, 101 classification of, by egg-laying sites, 137 habitats, 137 index to North American, 77

Overfishing of oyster beds, 131

Oxygen, effects of lack of, on sea-urchin, 99 physiological effects of lack, 99 reaction of fish to, 118 resistance to lack of, increased, 99

Oyster, 18, 114, 131

Oyster bank, 18 as social community, 132