944 



Development — (Continued) 



later, influence of quantitative and qual- 

 itative cleavages on, 334 

 periods of, xii 

 Developmental potencies, differences in 

 amphibian egg materials and 

 early blastomeres, 330 

 of isolated blastomeres of cleaving sea- 

 urchin egg, 329 

 de Winiwarter, H., 794, 795. 796 

 Diabetes, 875 

 Diakinesis, 128, 137 

 of hen's egg, 253 

 terminalization in, 139 

 Diaphragm, dorsal, 868 

 mammalian, 872 



origin of musculature of, 718 

 pulmonary, of chick, 872 

 Diaphysis, of bone, 691 

 Diarthrosis, 695 

 definition, 696 

 Dictyosomes, 126 



Didelphys, facial and cervical muscles de- 

 rived from hyoid arch mesoderm 

 in, 719 (see also Opossum) 

 pelvic girdle in, 689 

 Didelphys aurita, inner cell mass of blasto- 

 cyst of, 304 

 Didelphys virginiana, xx 

 blastula, formation of, 364 

 egg, characteristics of, 206t 

 fertilization, site of, 206t 

 inner cell mass of, 304 

 sperm entrance into egg, site of, 206t 

 uterine horn, anterior end of, 194 

 Diencephalon, 822 



thin roof plate of, 822 

 Diestrus, definition of, 93 



lactational, definition of, 94 

 Differentiation, biochemical, 375 

 definition of, 374 

 dependent, definition of, 375 

 implications of, 375 

 morphological, 375 

 physiological, 374 

 problem of, 374 

 Digestive tract, human, characteristics of 

 mucous membrane in, 620 

 structural composition of walls of, 629 

 Digestive tube, development of, 602 



diagrams showing basic features of, 

 598 

 general morphogenesis of, 602 

 Diphyodont dentition, 615 

 Diplonema stage, 137 (see also Diplotene 



stage) 

 Diplospondyly, 685, 688 



Diplotene stage, 128, 137 



of hen's egg, 253 

 Dipnoi, xvi 



Discoblastula, definition of, 341 

 Discoglossus, primitive frog, 187 

 Discoglossus pictus, xviii 



secretions causing lysis in, 229 

 Divergence, in gastrulation, definition of, 



398 

 Diverticulum, dorsal, left, 502 



right, 502 

 Division, meiotic (see Meiotic division) 

 Dizygomatic twins, definition of, 380 

 Dog (Canis familiaris), egg, characteristics 

 of, 207t 

 fertilization, site of, 207t 

 sperm entrance into egg, place of, 207t 

 Dog shark, development of intestine in, 



626 (see also Sqiialus) 

 Dogfish, Scyllium canicula, germinal vesi- 

 cle in, 136 

 Domm, L. V., 594, 892 

 Dornfeld, E. J., 119 

 Dorsal aorta (see Aorta, dorsal) 

 Dorsal arching movement, 461 

 Dorsal lip, of blastopore, of teleost blasto- 

 derm, 438 

 Dorsal median septum, 818 

 Dorsal root ganglion cells, 817 

 Dorsal septum, 706 

 Dorsal sulcus (fissure), 818 

 Dorsal upgrowth movement, 461, 476 

 Driesch, H., equipotential state of, 377 

 Dry fertilization, 232 

 Duct, ejaculatory, 20 

 epididymal, 15, 18 



convoluted, absence of, 28 

 function of, 29 

 presence of, 29 

 reproductive, 15 



and external fertilization, 17 

 and internal fertilization, 18 

 in male vertebrates, 757 

 sperm-conveying, 4 

 Ductuli efferentes, 15 

 Ductus choledochus, 627 

 Ductus deferens, 19 



cross section of ampullary region of, 183 

 muscular character of, 182 

 Ductus venosus, of chick embryo, 743 

 Dukes, H. H., 103 

 Dumas, 281 

 Dunn, L. C, 197 

 Dura mater, 822 

 Durken, B., 331 

 Dushane, G. P., 592, 593 

 Dyad, 132 



