INDEX OF SUBJECTS 
Owl, screech, 229. 
Oxygen: anaerobic animals, 133; bur- 
rowing dragon-fly nymphs, 142; circu- 
lation of, 61; correlated with age of 
ponds, 68-70; in lakes, 125, 133; in 
pools, 91; in springs, 93; in streams, 
103; intermittent quantities, 90; neces- 
sary in water, 59; not added by certain 
plants, 65; reduced by sewage, 17. 
Panther,)15, 238, 242. 
Partridge, 196. 
Perch: pirate, 120; yellow or American, 
85, 99, I19, 120, 126, 130, 156; trout- 
perch, 84. 
Pest species, number of, on different 
forest trees, 166. 
Pewee, wood, 242, 244. 
Phalangids, 167. 
Physiological agreement of communities: 
34; life histories, 33; proportionality 
in organisms, 26. 
Physiological equilibrium: 26; distrib- 
uted by changes in the organism, 30, 
by external conditions, 30; in relation 
to habitat, 31. 
Pickerel, grass, 105, I15, 142, 150. 
Pike: 85, 115, 120, 140; pike-perch, 85; 
wall-eyed, 85. 
Pintail, 17%. 
Planarians, in Lake Michigan, 77. 
Plankton: in arctic seas, 66; proportion 
to denitrification, 66; relation to tem- 
perature, 66, to COz, 67, 68, to oxygen, 
67, 68, to carbonates, 67, 68, to rate of 
flow, 67, to seasons, 67, to age of ponds, 
68, to moon, 67. 
Plants, aquatic: in sandy riffles, 99; in 
sluggish streams, 104; value of, to 
animals, 65, 142; watercress, 93. 
Plants, aquatic, scientific names: 
—Chara, 64, 65, 74, 142, 145, 148. 
—Cladophora, 64, 74. 
—HElodea, 65, 129. 
—Equisetum, 65, 151. 
—Myriophyllum, 65, 129, 130, 131, 145. 
—Nostoc, 74. 
—Potamogeton, 145. 
—Proserpinaca, 151. 
Plants, terrestrial, scientific names: 
—Arabis lyrata, 228. 
—Citrus, 257. 
—Gossypium, 257. 
—Hibiscus, 189. 
—Juncus balticus, 173. 
Ww 
On 
~I 
—Monarda, 228, 232. 
—Opuntia, 255. 
—Parnassia caroliniana, 182. 
—Pinus banksiana, 228. 
—Sagittaria, 175. 
—Tilia, 257. 
Plover, piping, 180. 
Polyzoa, scientific names: 
—Fredericella sultana, 84. 
—Paludicella ehrenbergii, 84. 
—Pectinatella magnifica, 128, 130, 135. 
—Plumatella, 84, 103, 121, 131: 
polymorpha, 135. 
Polyzoan, gelatin-secreting, 128, 129. 
Pond animals in streams, 102, 103. 
Pond communities: 136-57; temporary, 
173-80. i 
Ponds, vernal or temporary: forest, 179; 
snails of, 192; influence of rainfall on, 
177-79; vegetation choked, 174; young, 
with bare bottom, 173. 
Porcupine, Canada, 196. 
Prairie chicken, 167, 289. 
Prairie communities, 278-98. 
Pressure of water, 64. 
Protected situation of large lake, com- 
munities of, 8o. 
Protection of wild animals: 8-11; pro- 
tected species, 56, 57; wardens, 57. 
Proteid, foodstuffs, 66. 
Protozoa: 129, 130; anaerobic, 133; 
as animal food, 20; producers of disease, 
20. 
Protozoa, scientific names: 
—Actinophrys sol, 75. 
—Diffiugia: 
globulosa, 75. 
pyriformis, 132. 
—Peridinium tabulatum, 75. 
Psocus, 234. 
Pulmonate snails, aquatic 
of, 129. 
Pumpkin-seed, 84, 156. 
Puss caterpillar, behavior of, 232. 
respiration 
Quantity: of larger animals, 69; of life 
on land, 166; of plankton: causes of 
fluctuations in, 72; in different bodies 
of water, 67; in ponds of different 
ages, 69; in polar regions, 66; seasonal 
variation in, 67. 
Rabbit: 196; cottontail, 269, 275. 
Raccoon: 199, 202; eats crayfishes, go. 
