INDEX 



965 



Oken, 536 



Okkelbergia lamotteni, sea lamprey, xvi 



Okkelburg, P., 235 



Oldham, F. K., 884 



Olfactory nerve (cranial n. I), 827 



Olfactory organ, development of, 843 



Olfactory pits, 844 



Olfactory placode, 843, 844 



Oligodendroglia, 810 



Olsen, M. W., 287, 313, 320 



Omasum (Psalterium; Stomach manyplies), 



of cow's stomach, 623 

 Omental bursa, 873 

 "Omnis Cellula e Cellula," dictum of R. 



Virchow, 281 

 Omohyoid muscle, innervation of, 717 

 Omphalomesenteric veins, of chick em- 

 bryo, 743 

 Omphalos (Umbilical ring; Umbilicus), 912 

 Oncorhynchus tschawytscha, king salmon, 



xvii 

 Ontogeny, recapitulates phylogenetic pro- 

 cedures and not adult morpho- 

 logical stages, 351 

 Oocyte, (see also Egg) 



c>toplasm of, and formation of a second 



kind of yolk, 158 

 definition of, 68, 125, 154 

 degree of fusion with sperm at fertiliza- 

 tion, 212 

 inequality of cytoplasmic division in, 144 

 mammalian, membranes of, 168 

 maturation divisions in, as compared 

 with spermatocyte, 144 

 in relation to sperm entrance and egg 

 activation, 256, 269 

 membranes in relation to, 162 

 nucleus during meiotic prophase, 136 

 polarization of, 160 

 primary, 145 



primitive, characteristics of, 68 

 reptile, zona radiata (zona pellucida) of, 



167 

 secondary, 145 

 Oogonia, 1 14 



young, of fowl, 154 

 Ooplasmic movements, and sperm entry, 



243 

 Ooporphyrin pigments, 907 

 Ootid, 145 

 Opercular opening, of gill chamber in frog 



tadpole, 641 

 Operculum, formation of in frog tadpole, 

 461 

 of gill chamber, in teleost fishes, 639 

 Ophthalmicus (deep profundus), division 



of trigeminal nerve, 828 

 Opisthonephros, 773, 780 



Opossum, bifid penis in male, 196 



blastula of, formative cells of, 365, 366 



corpus luteum of, 84 



early development of blastoderm, 363 



female reproductive tract in, 196 



female suckling young, 929 



fertilization in, 252 



Graffian follicle in, mature, 72 



tertiary conditions of, 71 

 Graffian follicle in developing ovary, 70 

 pseudo-vaginal birth canal of, 63 

 relation of ovary to infundibulum in, 



194 

 reproductive system, female, 63, 64 

 young female, primitive germ cells near 

 germinal epithelium, 119 

 Oppenheimer, J. M., 287, 441 

 Opsanus (Batrachus) tan, origin of oral 



cavity in, 603 

 Optic evaginations, primary, 845 

 Optic lobes, 822 

 Optic nerve (cranial n. II), 827 

 Optic nerve fibers, decussation of, 827 

 Optic stalk, 845 

 Optic vesicles, 822 



primary and secondary, 845 

 Oral cavity, origin from stomodaeal invagi- 

 nation, 603 

 Oral evagination, of foregut, 482 

 Oral glands, 676 

 Oral membrane, 599 

 Organ, intromittent, 4, 18 

 Organ-forming areas, major, antero-pos- 

 terior extension of, 457 

 starting point for tubulation of, 459 

 major presumptive, of late blastula and 

 gastrula, summary of later deriv- 

 atives of, 533 

 relationships of at end of gastrulation 

 in anuran amphibia, 460 

 migration of in the amphibia, 409 

 of the chordate blastula, 352 

 presumptive, in amphibian late blastula, 

 355 

 of chick blastoderm, 360 

 of chordate blastula, 344 

 of late amphibian blastula, destiny of, 



354 

 of Salmo irideus (trout) blastoderm, 



369 

 of the blastula, principle of, 344 

 Organ-forming germ-regions, principle of, 



enunciated by Wilhelm His, 343 

 Organ of body, definition of, 517 

 Organ system, definition of, 518 



early, fundamental similarity of, 520 

 vertebrate, basic homology of, 545 

 Organism, definition of, 518 



