INDEX 



825 



Pinnipedes, pupils, 470, 612 



refraction of, 639 



retinal vascularization, 479 



sphincter muscle, 468 



tapetum cellulosuni, 457, 459, 609 

 Pipa americana, 334, 339 



pupils, 339 

 Piscicola, ocelli of, 193 

 Pithecanthropus, 445, 755 

 Pithecia. See Saki. 

 Pithecus. See Langur. 

 Pituitary gland, 538 



hormones and, 550 

 intra-ocular pressure and, 561 

 in vertebrates, 557 



hormone, photoperiodic changes and, 

 19 

 seasonal changes and, 21 

 Placentals, 429, 441 



colour vision in, 633 



decussation, chiasmal, 698 



diurnal, 604 



eyes of, 446 #., 607 



fundi, PL XIV, XV 



nocturnal, 604 



panoramic vision, 686 



pujiils, contractile, 612, 613 



spatial judgment, 704 



vision of, 601 



visual field, binocular, 687, 689 



See also Mammals. 

 Placode theory of origin of vertebrate eye, 



246 

 Placoderms, 234, 235 

 Placophora, 196 



ocelli of, 196 



See also Chiton. 

 Plagiostomum, activity of, 34 

 Plaice. See Pleiironectes platessa. 

 Planaria gonocephala, ocellus of, 134 

 phototactic reactions of, 572 



lugubris, phototaxis in, 43, 45 



maculata, tropotaxis in, 55 



torva, visual cells of, 128, 134 

 Planarians, 34, 187 



cave-dwelling, eyes of, 724 



nervous system, 519 



orthokinesis in, 34 



phototactic response in, 33, 572 

 Planes, colour changes in, 92 

 Plants, distinction from animals, 510 



floral initiation in, 10 



hormones in, 12, 39 



Plants, long-day, 11 



photoperiodism in, 9 



photoreceptors in, 116 



photosynthesis in, 4 



short -day, 11 

 Platyhelminthes, 187 



contraction in light, 7 



sense organs of, 188 



See also Turbellarians, etc. 

 Platypus, 430, 431 



ciliary body, 434 



eye of, 432 



posterior segment of, 433 



retina, 435 



scleral cartilage, 433 

 Plecoptera, 218, 220 

 Plecostomus, pvipil, 304, 329 

 Pleiirodeles, iris vascularization, 347 

 Pleuronectes, ocular movements in, 693 



flesus, pupil, 304 



platessa, camouflage in, 83 

 Plexippus sinuatus, eyes of, 212 

 Plusia gamma, olfactory sense of, 581 



pigment migration in, 19 

 control of, 556 

 Podargus, pecten, 412 

 Poikilochromic animals, 82 

 Polarized light, orientation to, 66 



mechanism of, 174 

 Polecat {Putorius putorius), 444, 445 



colour blindness of, 634 



threshold to light, difference, 618 

 Polycelis coronata, ocelli of, 188 

 Polychsetes, 190 



accommodation in, 591 



bioluminescence in, 739, 745, 748 



colour changes in, 93 



conditioning of, 573 



degenerate eyes in, 729 



light-shadow reflex in, 573 



nervous system, 520 



ocelli of, i91 



reproductive cycle of, 18 

 Polyclad worms, 187 

 eyes of, 188 



neuro -endocrine system, 552 

 See also Leptoplana. 

 Polyipnus, optic nerve of, 310 

 Polyodon, 315 



Polyophthahnus pictus, ocelli of, 130, 191 

 Polypedates reinwardti, pupil, 339 

 Polyphemus, 209 



eyes of, 163, 209 



