964 



Neural tube, bilateral symmetry of, 513 



dependency of upon surrounding tissues, 

 513 



developing, structure of, 8J0 



histogenetic zones of, 816 



supporting tissue of, development of, 816 

 Neuralization, definition of, 465 



neural fold method of, 466 



thickened keel method of, 465 

 Neuraxis, 814 

 Neurenteric canal, 471 



formation of in frog embryo, 469 



in Amphioxus, 497 

 Neurilemma (sheath of Schwann), 819 

 Neurobiotaxis, definition of, 824 

 Neuroblasts, apolar, 807, 815 



bipolar, 815 



primitive, 814 



unipolar, 815 

 Neurocoels, 822, 858 

 Neurocranium, 668 



basic cartilaginous foundation of, 652 



definition of, 669 



development of, 669 



development of in Amia calva, bowfin, 

 670 



developmental stages in frog, 672 



developmental stages of in bird, 673 



mammalian, developmental stages of, 

 675 



of chicks, 678 



of frog. 676 



of human, 680 



types of in vertebrates, 669 

 Neurofibrils, 814 

 Neuroglia, 809 

 Neuroglia cells, 810, 816 

 Neurohumoral substances, 594, 838 

 Neuromast system, 813 

 Neuromasts, 842, 854 

 Neuromeres. 812, 813 

 Neuron structure and relationships, 808 

 Neuron theory (doctrine), of nervous 



structure, 807 

 Neurons, afferent, 826 



association, 809 



cytoplasmic changes of, 814 



formation of, 814 



multipolar, 815 



nuclear changes of, 815 

 Neuroplasm, 814 

 Neuropore, anterior, 471, 497 



posterior, 471 

 Neurosensory cells, of olfactory epithe- 

 lium, 843 

 Neurula, 468 

 Newport, 213, 281 



Nickerson, W. S., 564 



Nictitating membrane, 853 



Nieuwkoop, P. D.. 120 



Nipple (teat), 589 

 eversion, 589 

 inversion, 589 



Nissl substance, 815 



Noback, C. R., 927 



Noble, G. K., 189, 591 



Nodose ganglia, of vagus nerve, 831 



Normality, male, effects of FSH and LH 

 upon, 41 



Notochord, a specialized, median portion 

 of middle germ layer of meso- 

 dermal tissue, 493 

 position of in embryo of Amphioxus, 



494 

 position of in vertebrate embryo, 494 



Notochordal area, as center of organization 

 of the late blastula, 350 

 of late blastula and gastrula, later de- 

 rivatives of, 533 



Notochordal canal, 417 

 in human gastrula, 432 



Notochordal-neural canal, 474 



Nourishment, in relation to testicular 

 function, 38 

 of young, 899 



Nuclear changes, of developing neurons, 

 815 



Nuclear equality, of cleavage blastomeres, 

 328 



Nuclear pole, of egg and sperm entrance, 

 259 



Nucleated (mantle) zone, middle, of neu- 

 ral tube, 817 



Nucleation, delayed, in developing egg of 

 Tritiirus viridescens, 332 



Nucleolus, of developing neuroblast, 815 



Nucleus, metamorphosis of, during 

 spermiogenesis, 153 



Nucleus ambiguus, of vagus nerve, 831 



Nucleus pulposus (pulpy nucleus), 682 



"Nurse cells," 147 



Nussbaum, M., 114 



Nutrition, circulatory system in relation to, 

 927 

 histotrophic, 921 



Occipital bone, development of in human, 



695 

 Oculomotor nerve (cranial n. Ill), 827 

 O'Donoghue, C. H., 197 

 Odontoblasts, 61 1 



dentinal fibers of, 611 



in skin of shark embryo, 562 

 Odontoceti, xxi 



