INDEX 



Phcnotypc, 176 



Phoronidea, 216, 221 



Phosphaa;ens, 543 



Phosphate, 119 



Phospholipids. 26, 76, 78 



Phosphoric acid, 27 



Phosphorus. 29 



Pho.sphorvlase, 120, 121 



Phosphor\lation, 36, 75 



Phot opsin, 107 



Photoreceptors, in Bmnchiosloma, 552 



Photosvnthetic protozoans, 605 



Phvla, of Animal Kins^dom, 216; interrela- 

 tionships, 221 



Phyllodoce. protonephridium of, 520 



Phylos;enetic tree, of Animal Kina;dom, 219 



Ph\io^env, 633 



Phvlum, defined, 220 



Physalw, 303 



Physeler, 589 



Physical sciences, 7 



Physicochemical factors of environment, 594, 

 596-605 



Physiological difTerentiation, of Paramecium, 

 256 



Physiological genetics, 197 



Physiological isolation, 653 



Physiologically balanced cells, 229 



Physiology, 8 



Phytomastigina, 266 



Pia mater, 89 



Pickerel, 606, 611 



Pickerel frog, 215 



Pigment cells, 1 18 



Pigment granules, 20, 60 



Pigmented epithelium, 60 



Pilidium, 342, 343 



Piloerection, 126 



Pinctada, 379 



Pinocytosis, 19 



Pipefish, 559 



Pisces, 216, 541, 554 560 



Pithecanthropus erectus, 639, 640; P. pekmerms, 

 640 



Pituitary gland, 527; see also Hypophysis 



Placenta, 31, 95, 124, 163; of Eutheria, 585 



Placental mammals, 123 



Placenticeras, 624 



Placohdella, 419 



Placodermi, 216, 541 



Plan and purpose, in evolution, 653 



Planaria oonocephala, 319 



Planarians, 315, 316, 413, 530, 535 



Planocera, 326 



Plant Kingdom, 218 



Plant-like protozoans, 510 



Planula larva, 301, 302, 308, 313 



Plasma, 63, 64, 66, 83 



Plasma membrane, 19 



Plasmagel, 232 



Plasmalcmma, 230 



Plasmasol, 232 



Plasmodium, 246; P. cynomo/oi, 247; /■". matariae, 

 246 



Plasmodroma, 216, 229 



Platelets, 64 



Platyhelminthes, 216, 219, 221, 314-340, 356; 

 cuticle of, 528; distribution of nutrients in, 

 513; protonephridia in, 519; reproductive 

 system in, 532 



Platypus, 579, 581, 582, 608 



Plalysamia, 466, 467, 468 



Pleistocene Period, and extinction of Ameri- 

 can horses, 625; and human evolution, 640; 

 glaciations of, 644; Ice Age, 641 



Pleodonna califormca, 267; P. ilbnoisensis, 267 



Pleopod, of crayfish, 428; of lobster, 427 



Plerocercoid, 339, 340 



Plesiosaurs, 567 



Pleural cavity, 48, 56 



Pleurohrachia, 312 



Pleurobranchiae, 429 



Pleurocystites, 487 



Pleuroperitoneal cavity, 48, 56, 129 



Plumatella, 361 



Pluteus larva, 509; see also Echinopluteus 

 larva and Ophiopluteus larva 



Podobranchiae, 429 



Podokesaurus, 569 



Podophrya, 258, 259 



Pogonophora, 221 



Point Barrow, early man at, 644 



Polar bodies, 135 



Polar cell, 139 



Polistes, 470 



Polocvte, see Polar cell 



Polvchaeta, 216, 396, 398-402, 516 



Polycladida, 316, 326, 327 



Polyembryony, in insects, 209, 534; in trema- 

 todes, 332, 530 



Polyoordius, 417, 418 



Polygyra, 386 



Polymorphism, in Physalia, 303 



Polyodon, 558 



Polypeptides, 27, 72, 118 



Polyps, of hydromedusae, 301, 302; of Scypho- 

 medusae, 305; of sea fan, 309 



Polypterus, 558 



Polysaccharides, 26, 30 



Polyspermy, 144 



Pnmncanthus, 560 



Pongidae, 638 



Ponoo, 587 



Popillui, 466 



Population growth, 610; events in, 61 1 



Populations, 174 



Porcupine, 580 



Pores, of olynthus, 275 



Porifera, 216, 219, 221, 224, 273-283, 518, 

 522,531 



700 



