434 



INDEX 



Plate on heredity, 225 

 Platodes, 263, 279 

 Play, analysis of, 60-77 



„ animal, 60-77 

 Plural variations, 259 

 Plesiosaurus, the, 120 

 Plectognathic fishes, 177 

 Poisoning of germs, 223 

 Poisonous butterflies, 148 



„ organisms, colours of, 147 



„ snakes, 139, 143 

 Polar animals, colour of, 54-5 

 Political systems, development of, 



413 

 Pollen, 197 

 Polyp, the, 284, 291 

 Pond, inhabitants of the, 2i 

 Pond-mussel, the, 175 

 Pond-snail, the, 239 

 Porto Santo rabbit, the, 34 

 Potential immortality, 307 

 Presentiment of the bird, 107 

 Preyer on the nature of life, 315 

 Proboscis of butterfly, 201-2 

 Processional butterfly, 43 

 Proper names, 393 

 Protective colours of insects, 189 

 Protoplasm, 289 

 Protozoa, the, 170, 263, 292 

 Psychic phenomena, 384 



,, „ in inorganic 



matter, 404 

 Psychic phenomena in the protists, 



403 

 Psychology, 384 

 Pterodactyl, the, 121 

 Pterosauri, the, 120, 130 

 Pupa, the, 188, 206 

 Purpose in organisms, 354 

 „ in science, 373 



Racial colours, cause of, 165 

 Reality, nature of, 395 



„ not given in natural science, 



383 

 Recreation not the essence of play, 



61 

 Red breast in birds, 81, 82 

 Redstart, the, 45 

 Reduction cleavage, 321 

 Reflex action, 64, 214 

 Regeneration of organs, 142 

 Regions of nature, 20 

 Regulation of rivers, 177 

 Reproduction, essence of, 294 



„ rate of, 58 



Reptiles, age of, 135 

 Rhine salmon, 48 



Rhodeus, the, 175 

 Richard's pipit, the, 109 

 Rigid types, 132 

 Ringed adder, the, 139, 148 

 Rivers, artificial control of, 48 

 Rock-pigeon, the, 30 

 Rudimentary organs, 158-70 



„ parts in germs, 295 



Ruffe, the, 178 

 Rut of animals, 57 



Sacculina, 246 

 Salamander, the, 37 



„ and fire, 146 



Salmon, spawning of the, 180-1 

 Satyridas, the, 188 

 Scar in the egg, 304 

 Scars, use of, 144 

 Scented butterflies, 195 

 Schiller on play, 62 

 Science, objectivity of, 391 

 Scientific explanation, nature of, 361 

 Scolices, 280-1 

 Sea-anemones, 285 

 Seed of plants, 198 

 Selective value, 329 

 Self-correction of determinants, 336 

 Self-deception in play and art, 71-2 

 Self-preservation, instinct of, 356 

 Sensations as psychic elements, 384 

 Sense-impressions, 65 

 Sense of life, 426-7 

 Senses, action of the, 391 

 Serpent, habits of the, 138 



„ movements of the, 140 

 Sexual characters, 82-5 



„ generation, nature of, 299 



„ selection, 80-3 



„ „ teleological, 370 



„ union, reasons for, 256 

 Shad, the, 173 

 Shamming death, 193, 216 

 Shell of the snails, origin of the, 241 

 Silurian strata, animals in the, 121 

 Skeleton of the articulates, 203 

 Skull, development of the, 153 

 Smooth adder, the, 141 

 Snail, the, 239 



„ breathing of the, 244 

 Snails with small shells, 168 

 Snipe, noise of the, 96 

 Social instincts, culture of, 408 



„ instinct in birds, 112 

 Society, growth of, 407 

 Sociology, 406 



„ laws of, 407 



Species, nature of a, 33, 117 



persistence of, 132-3, 135 



