Index -7Y7 



Plasma membrane, 16, 31-33, 112; capacity of 



various substances to penetrate, 116; passive 



permeability of, 116-17 

 Plasmagel, 197 

 Plasmodium, 602 

 Plastids, 28 



Platelets, 289, 321, 323 

 Plalyhelminthcs (flatworms), 635-41; Cestoidea, 



639-41; characteristics of, 636-37; classes of. 



637-41; phylogeny of, 641; Trematoda, 637-39; 



Turbellaria, 637 

 Pleistocene epoch, 559, 570 

 Pleura, 285, 359. 360 

 Pleural cavity, 360 

 Plumules, 223 

 Pneumatophores, 586, 587 

 Polar bodies, 271, 272, 277. 478 

 Polarity, molecular, 92 

 Pole cells, 279 

 Pollen tube, 221 

 Pollination, 221 

 Polyehaela, 649 

 Polyembryony. 395, 499 

 Polymolecular energy, 66 

 Polyneuritis, 351 

 Polypeptides, 412 

 Polypodium scouleri, 204 

 Polysaccharides, 80 

 Polytrichum, 212 

 Population, animal, food supply and, 574-75; 



genetics, 504-05; increases in, limits of. 539-41 

 Pore cells, 240 

 Pores, 240, 249, 292, 370 

 Porijera, 291-92, 629-30 

 Porphyra, 601 

 Porter, K., 196, 533 

 Portuguese man-of-war, 630 

 Posterior lobe, pituitary gland. 409, 410; hormones 



of. 412 

 "Potassium jump," 123 

 Potential energy, 66, 71 

 Potentials, action, 190, 191, 192-93, 260, 428, 



429,448; bioelectric, 190, 191-92; generator, 428, 



429, 456: pacemaker, 456; resting, 191, 192-93 

 Predatism, 575-76 

 Prediction, in scientific method, 13 

 Pregnancy, progesterone as factor in, 402; test of, 



413 

 Pressure as abiotic environment, 584-85 

 Priestley, J., 159 



Primary germ layers, 278; contributions of, 284 

 Primary spermatocyte, 52, 53 

 Primates, 676 



Primitive vascular tissue, 240, 241 

 Principles, cell, 16, 38-39; in scientific method, 



14-15 

 Proboscidea, 676 



Proboscis worms, 641 



Producers, 587, 588, 589 



Progesterone, 388, 400, 401; factor in pregnancy, 

 402 



Pronephros, 284 



Propane, organic compound, 77 



Prophase, in mitosis, 41-44, 45 



Proprioceptors, 420, 425, 460 



Prostate glands, 384, 385 



Prosthetic group. 104 



Proteases, 101, 102-03, 130, 306 



Protein synthesis, 133-35, 137-39; in green plants, 

 169; mechanisms of, 134 



Proteins, 6, 10 n.. 76, 83-89, 320; amino acids, 

 84-85; in common foods, character of, 347; 

 conjugated, 88-89, 104; DNA, 16, 22, 23, 35. 47. 

 83, 88, 110, 134-35; food substance, 127; mole- 

 cules, 3-dimcnsional configuration of, 87-88: 

 peptide bonding in relation to, 85; RNA, 22. 

 23, 25, 35, 83, 88, 110, 134-35; simple vs. con- 

 jugated, 88-89; specificity of, 85-87 



Protenor, 498 



Proterozoic era, 563, 564, 565, 566 



Prothallia, 204, 207 



Prothrombase, 323, 353; synthesis of, 343 



Protococcus, 168 



Protonema, 214 



Protoneurons, 450 



Protons, 69 



Protoplasm, 6-7; adrenalin in, 89; Brownian 

 movement in, 92; carbohydrates in, 76-80, 89: 

 cell and, 16-35; cellular structure of, 6-7; chem- 

 ical composition of (see Chemical composition 

 of protoplasm); chemical structure of, 6; col- 

 loidal size range of, 91-92; composition of, 

 average, 89; constituents in, elementary, 65-66; 

 crystalloidal range of, 91-92; energy transmit- 

 ters in, 89; gases in, 75; hormones in, 89: inor- 

 ganic components of, 71-75; ions in, main or- 

 ganic, 74-75; life and, 5-7; lipids in, 76, 80-83, 

 89; liquid system, 19; molecular pattern of, 64; 

 organic components of, 76-90; organic wastes 

 in, 89; physical structure of (see Physical struc- 

 ture of protoplasm); proteins in, 76, 83-89; 

 shrinking of, 33; vitamins in, 89; water in, 72- 

 75, 89 



Protoplasmic surfaces, 95 



Prololheria, 673 



Protozoa, 49, 55, 119, 122, 195-96, 291, 369, 

 625-28; Ciliophora, 625, 627-28; Mastigophora, 

 625, 626-27; nutrition of, 128-33; Sarcodina, 

 625-26; Sporozoa, 625, 628 



Protozoology, 14 



Provitamin, 350, 353 



Psalliota campestris, 606, 607 



Pseudopodia, 128, 129, 196 



Psilopsida, 611-12 



