326 



INDEX 



Olfactory nerve, 165, 168 



Olfactory pit (see also Nasal pit), 168 



of pig, 10-mm., 272 

 Olfactory placode (see also Nasal plac- 

 ode), 



of chick, 

 48-hr., 220 

 72-hr., 225 

 Oocyte, 305 



Operculum, of frog, 139 

 Optic chiasma, 165 

 Optic cup, 169, 170 



in chick, 



48-hr., 219, 220 

 72-hr., 225 



in frog, 134 



neuroblasts in, 144 

 Optic lobes, 166 

 Optic nerve, 167, 169, 170 



formation of, 144 



in human, 282 

 Optic recess, 164, 165 

 Optic stalk, 144, 169 



of chick, 

 48-hr., 219 

 72-hr., 225 

 Optic vesicle, 70, 167, 169 



in frog, 103 



inducing property of, 104 

 Oral cavity, 



in chick, 72-hr., 224 

 Oral evagination, 135 

 Oral plate, 187 

 Organization, 



of amphibian egg, 56 



labile nature of, 33 



of sea urchin egg, 32 



theories of, 39, 40, 41 

 Organizer, 



in amphibian, 78 



chemical nature of, 84, 85 



in chick, 81 



denned, 79 



for head, 88, 89 



regional differences in, 88, 89 



theory of action of, 86, 90 



for trunk, 88, 89 

 Orientation, of tissue culture media, 151, 



152 

 Otic pits, 167, 168 

 Otocyst (internal ear, otic vesicle), 



in amphibian, 70 



Otocyst — (Continued) 



in chick, 

 48-hr., 219 

 72-hr., 223, 224 



field of, 102 



in frog, 135, 136 



of -human, 276 



of pig, 10-mm., 272 

 Outgrowth of nerve fiber, 



effect of orientation on, 151, 152 



to limb, 148, 149 



along optic stalk, 144 



theories of, 149, 150, 151 



in tissue culture, 143 

 Ovarian cycle, effect of pituitary hormones 



on, 258, 263 

 Ovary, 



development of, 299, 300, 301 



in human development, 282 



release of egg from, 1 5 

 Ovulation, 15, 16 



control of, 



by hormone, 21 

 by light, 19 



inhibition of, by pregnancy, 261 



in mammals, 20, 21 

 Ovum (see Egg) 

 Oxygen, effect of, on polarity, 233 



Pancreas, 190 



in human, 278 

 Pancreatic ducts, 190 

 Parthenogenesis, artificial, 4, 47 

 Parturition (see Birth) 

 Paternal chromosomes, 304 

 Periblast (see Marginal periblast) 

 Peritoneum, origin of, 200 

 Pharynx (see also Foregut) , 



of chick, 



48-hr., 278. 219 

 72-hr., 224 



derivatives of, 187, 188 



of frog, 134 



of pig, 10-mm., 272 

 Photoreceptors, 169, 170 

 Pigment cells, 160, 161 

 Pigment layer of retina, 134 

 Pituitary gland, 70 



development of, in human, 282 



effect of, on pregnancy, 262, 263 



function of, 133 



role in ovulation of, 17, 259 



