INDEX 



663 



Pisces, 103, 105 



Pistils, 497 



Pithecanthropus, 555, 560, 637 



Pitli rays, 2^7, 249 



Pituitary gland, 348, 397, 398, 399 



anterior lobe, 400 



intermediate lobe, 400 

 Placenta, 427, 428 

 Planaria, 85 



Plankton, 13, lA, 21, 22 

 Planta, bee, 207 

 Plant and animal cells, functional 



differences, 166-167 

 Plant breeding, methods of, 571-573 

 Plantigrade feet, 333 

 Plant lice, 413 



Plant parasites, 216, 223, 288 

 Plants 



harm done by, 579-582 



long and short day, 12, 13 



parts of, 238-240 ' 



role of green, 237-273 



small, in fresh water, 153-154 



types of, 239 

 Plants and animals 



cells of, 139-140 



economic values of, 573-579 

 Planula, Obeha, 185, 186 

 Plasma, 303 

 Plasmodium, 77, 227 

 Plasmolysis, 136 



Plastids, part played by, in heredity, 465 

 Platelets, 311 

 Platyhelminthes, 85, 103 

 Plecoptera, 100 



Pleistocene period, 476, 477, 509, 513, 

 553, 554, 555, 557, 560, 565, 637 

 Plesippus, 511 

 Pleurococcus, 169 

 Plicae circulares, 284, 291 

 Pliocene period, 476, 511, 513, 555 

 Pliohippus, 511 

 Ploidy, 457 

 Plovers, 114 

 Poebrotherium, 509 

 Poisons, honey bee, 212 

 Polar bodies, 430 

 Polarity, 381 

 Poles, 561 

 Poliomvehtis, 620 

 Pollen basket, 207 

 Pollen brush, 207 

 Pollen comb, 207, 208 

 Pollen grains, 177 

 Pcjlygordius, 93 

 Polvnesians, 562 

 Polyps, 81 



Obelia, 185 

 Polysiphonia, 71 



Polystoma, 85 



Pons varolii, 350 



Populations, factors in changing, 34-38, 



41 

 Porcupines, 505 

 Porifera, 79, 103 

 Portuguese, 561 



Posterior lobe, pituitary, 400, 402 

 Posterior nares, 287 

 Posterior peduncles, 351 

 Post-glacial period, 476, 513 

 Potassium, 277 

 Poultry, 515 

 Precipitins, 626 

 Preformation, 431 

 Premolars, 286 

 Pressure 



effect on adaptations, 490, 491 



oxygen, 316 

 Pressure receptors, 362, 363 

 Priestley, 312 

 Primary oocytes, 430 

 Primary spermatocvte, 429 

 Primates, 115, 233,\534, 540, 541 

 Primitive streak, 420 

 Primitive vascular plants, 75 

 Primordial germ cells, 428 

 Primroses, 436 

 Proboscidea, 117 

 Proboscis, bee, 204, 205 

 Procamelus, 509 

 Procellariiformes, 113 

 Prochordates, 340 

 Progestin, 399 

 Proglottid, 226 

 Prophase, 141, 142 

 Propolis, bee glue, 213 

 Prosecretin, 392 

 Prosencephalon, 346 

 Prostomium, 188 

 Protection of embryo, 422 

 Protective coloration, 492 

 Protein elimination, 321 

 Proteins, 276, 282 



in plant synthesis, 262 



split, 621 ■ 

 Froteocephalus ambloplitis, 229, 230 

 Proteoses, 294 



Proterozoic era, 475, 476, 513 

 Protonema, moss, 176 

 Protoplasm 



colloidal nature of, 132-133 



composition of, 128, 131-132 



in cell, 128-130 

 Protoplasmic extensions, 335 

 Protoplasmic strands, 338 

 Protoplast, 169 

 Protopterus, 107 

 Prototheria, 115 



