292 
Parameecium, motor reflex, 15, 73, 
74, 76 
reaction to ultra violet rays, 
75 
swimming, 72 
thermotaxis, 58, 75 
thigmotaxis, 35, 73, 76 
Parker, G. H., food taking in 
anemones, 150, 151 
geotaxis of Labidocera, 31 
phototaxis of Labidocera, 31, 
50; of Vanessa, 55 
Parrot imitation, 257 
Patellas, homing, 188 
Pawlow, J. P., formation of habits 
by stomach, 159 
Peal, imitation in jungle pheasant, 
254 
R., 163, goniotaxis in 
Planaria, 36 
reactions of Planaria, 53, 147 
variability in behavior of 
Planaria, 147 
Pechuel-Lésche, E., intelligence of 
baboons, 267, 269 
Peckham, G. W. and E. G., 216, 
homing of wasps, 193-196 
instincts of solitary wasp, 119, 
* 120, 131, 132 
intelligence in solitary wasp, 
203, 204 
variability of instinct in soli- 
tary wasp, 131, 132 
Perch, intelligence, 220, 221 
Pfeffer, W., chemotaxis of bacteria, 
22 
Pearl, 
chemotaxis of spermatozoids | 
of ferns and mosses, 26 
Pfungst, O., 258 
Phototaxis, 19-21, 36, 38, 40 ff, 82, 
186, 192 
Photokinesis, 41, 42 
Pieron, H., intelligence of Cras- 
sius, 221 
intelligence of Triton, 227 
kinesthetic reflex, 199 
INDEX 
Pigeon, compensatory motions, 39 
Pike, intelligence, 219 
Planaria, reactions to chemicals, 
28, 53 
reactions to light, 41 
reactions to mechanical stimu- 
lation, 53, 141 
reactions to repeated stimula- 
tion, 141 
thigmotaxis, 36 
varied response to stimuli, 
144, 147 
Plants, reactions, 15 
Play instinct, 109 
Pleasure, 6, 55, 164 ff 
Pleurosigma, tidal rhythms, 156 
Polistes, intelligence, 195, 196 
Polyergus, stupidity, 210, 211 
variation in cocoon spinning, 
132, 133 
Polytoma, lack of chemotaxis, 25 
Pouchet, G., phototaxis of Temora, 
50 
Preyer, W., 163, behavior of star- 
fish, 181 
human instincts, 100 
Promethus moth, instincts of, 124, 
125 
Protozoa, internally initiated activ- 
ity, 109° 
intelligence, 63-65, 86 ff, 181 
reactions, 15, 21 ff, 44—47, 49, 
58-60, 63 ff, 140, 141, 150 
rhythms, 16 
tropisms, 18, 21 ff, 44-47, 49, 
58-60, 70 ff 
Prowazek, S. von, 90 
Psammobia, reaction to light, 41 
Pitter, A., 61, 90_ 
Pycnogonids, phototaxis, 56 
Raccoon, intelligence, 242-245, 255 
Radl, E., 62, hovering in flies, 38 
movement of eye of Daphnia, 
57 
