INDEX 



469 



Omphalomesenteric arteries, 199,363; 

 veins, 364-366 



Ootid, 14 



Opaque area, see area opaca 



Optic cup, 165, 271 ; lobes, 251 ; nerve, 

 283, 284, 285; stalk, 149, 164, 284, 

 285; vesicles, accessory, 164 



Optic vesicles, primary, 108, 164; 

 secondary, 166 



Ora serrata, 272 



Oral cavity, 215, 216, 301 



Oral glands, 306 



Oral plate, 95, 173 



Orientation of embryo on yolk, 25, 63 



Ossification, 408-411; endochondral, 

 409; perichondral, 408 



Ostium tubse abdominale, 23 ; devel- 

 opment of, 402, 403; relation to 

 pronephros, 402 



Otocyst, 168; later development of, 

 289; method of closure, 168 



Ovary, 22, 398 -401 ; degeneration of 

 right, 398 



Oviducal membranes of ovum, 10 



Oviduct, 22; later development of, 

 403 



Ovocyte, 13, 26, 27 



Ovogenesis, 12, 26 



Ovogonia, 12, 26 



Ovum, 2. 10; bilateral symmetry of, 

 15; follicular membrane of, 10; or- 

 ganization of, 14; polarity of, 14 



Palate, 285, 299 



Palatine glands, 306 



Palingenetic aspects of development, 



6 

 Pancreas, 181, 323-325, 347 

 Pander's nucleus, 19 

 Papillae conjunctivae sclerse, 280 

 Parabronchi, 328 

 Parachordals, 428, 429 

 Paradidymis, 391, 398 

 Paraphysis, 248 

 Parencephalon, 108, 153, 249 

 Parietal cavity, 92, 116, 207, 208^ 



333, 334 

 Paroophoron, 401 

 Pars copularis (of tongue), 305 

 Pars inferior lal)yrinthi, 289, 293 

 Pars superior lal)yrinthi, 289, 291 

 Parthenogenetic cleavage, 35 

 Patella, 441 

 Pecten, 281, 282 

 Pectoral girdle, 434-436 

 Pellucid area (see area pellucidr.) 

 Pelvic girdle, 438-440 

 Periaxial cords, 158, 159, 161 

 Pericardiaco-peritoneal membrane, 



338 



Pericardial and pleuroperitoneal cav- 

 ities, separation of, 333 



Pericardium, closure of dorsal open- 

 ing of, 337; formation of mem- 

 branous, 338; see parietal cavity. 



Periblast, 38, 43, 47; marginal and 

 central 48; nuclei, origin of, 47, 48 



Perichondrium, 408 



Periderm, 304 



Perilymph, 296, 297 



Periosteum, 409 



Peripheral nervous system, develop- 

 ment of, 252 



Pfliiger, cords of, 399 



Phaeochrome tissue, 404 



Phalanges, 436, 438; of foot, 441; of 

 wing, 438 



Pharynx, derivatives of, 306; early 

 development of, 93-95, 173; post- 

 branchial portion of, 178 



Phylogenetic reduction of skeleton, 

 411 



Physiological zero of development, 65 



Physiology of development, 6 



Pineal bodv, 153, 249 



Placodes, 160, 161 



Pleural and peritoneal cavities, sep- 

 aration of, 340 



Pleural grooves, 208, 209 



Pleuro-pericardial membrane, 338 



Pleuroperitoneal membrane, 326 ; 

 septum, 340, 341 



Plica encephali ventralis, 149, 245 



Plica mesogastrica, 341, 344, 368 



Pneumato-enteric recesses, 209, 340 



Pneumatogastric nerve, 268 



Polar bodies, 13, 34 



Polyspermy, 35, 36, 37 



Pons, 252 



Pontine flexure, 149, 245 



Postanal gut, 182 



Postbranchial l)odies, 307, 309 



Posterior intestinal portal, 132 



Postotic neural crest, 160, 161 



Precardial plate, 334, 338 



Preformation, 6 



Pre-oral gut, 174 



Pre-oral visceral furrows, 174, 175 



Preotic neural crest, 158 



Primitive groove, 72 



Primitive intestine, 55 



Primitive knot, 73 



Primitive mouth, 55, 82 



Primitive ova, 26, 392, 399 



Primitive pit, 73 



Primitive plate, 73 



Primitive streak, 69; interpretation 

 of, 82; origin of, 74; relation to 

 embryo, 85 



Primordia, embryonic, 8 



