INDEX 
Omphalomesenterie arteries, 199,363 ; 
veins, 364-366 
O6tid, 14 
Opaque area, see area opaca 
Optie cup, 165, 271; lobes, 251; nerve, 
283, 284, 285; stalk, 149, 164, 284, 
285; vesicles, accessory, 164 
Optic vesicles, primary, 108, 
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 tubze 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 
164; 
Palate, 285, 299 
Palatine glands, 306 
Palingenetic aspects of development, 
6 
Pancreas, 181, 323-325, 347 
Pander’s nucleus, 19 
Papillzee conjunctive 
Parabronchi, 328 
Parachordals, 428, 429 
Paradidymis, 391, 398 
Paraphysis, 248 
Parencephalon, 108, 153, 249 
Parietal cavity, 92, 116, 207, 208, 
303, 334 
Paroéphcron, 401 
Pars copularis (of tongue), 305 
Pars inferior labyrinthi, 289, 293 
Pars superior labyrinthi, 289, 291 
Parthenogenetice cleavage, 35 
Patella, 441 
Pecten, 281, 282 
Pectoral girdle, 434-436 
Pellucid area (see area pellucida) 
Pelvie girdle, 488-440 
Periaxial cords, 158, 159, 161 
Pericardiaco-peritoneal © membrane, 
338 
scleree, 280 
469 
Pericardial and pleuroperitoneal cay- 
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 
Pheeochrome 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 body, 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 
Pneumatogastriec nerve, 268 
Polar bodies, 13, 34 
Polyspermy, 35, 36, 37 
Pons, 252 
Pontine flexure, 149, 245 
Postanal gut, 182 
Postbranchial bodies, 307, 309 
Posterior intestinal portal, 132 
Postotie 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, &5 
Primordia, embryonic, 8 
