961 



Metencephalon, 822 

 Metenteron, definition of, 597 



development of, 602 



early, main types of, 597 



esophagus and stomach region of, mor- 

 phogenesis and histogenesis of, 

 621 



hepato-pancreatic area, morphogenesis 

 and histogenesis of, 623 



primitive, basic cellular units of, 600 



tubular, formation of in flat blastoderms, 

 482 

 Metestrus, definition of, 94 

 Miastor, chromatin diminution in, 118 



early development of, 118 

 Microglia, 810 

 Micromastia, 590 

 Micropyle, 167, 257 



in egg of Bathygohius soporator, 249 

 Midbrain, 812 

 Middle ear, 557 



development of, 855 

 Middle piece, of sperm, 149 

 Midgut. 478, 600 



junction with hindgut, diverticula of, 601 

 Milk (deciduous) teeth, 613 

 Milk ridges, 587 

 Miller, A. M., 746 

 Miller, D. F., 927 

 Minot, C. S., 498 

 Mintz, B.. 892 

 Mitchell, G. A. G., 6 

 Mitochondria, 126, 157 



role of in fat formation, 664 



transformation into yolk spheres, 156 

 Mitochondrial body, or nebenkern, 152 

 Mitochondrial cloud, 159 

 Mitochondrial material, role in formation 



of middle piece of sperm, 152 

 Mitochondrial yolk body, 159 

 Mitosis. 281 



mechanisms associated with, 284 

 Molgula manhattensis, xv 

 Molva (ling), lack of parental care in, 900 

 Monad condition, of developing gamete, 



133 

 Monestrus, definition of, 94 

 Monkey, implantation of embryo, 919, 922 

 Monoblasts, 733, 736 

 Monocyte, 733, 736 

 Monoploid condition, of developing 



gamete, 133 

 Monotremata, egg transport through Fal- 

 lopian tube in, 904 

 Monozygotic twins, definition of. 380 

 Moore, Carl R., 35, 119, 885, 892 

 Moore, J. A., 297 

 Morgan, T. H., 216, 297, 382 



Morphogenesis, definition of, 517 

 Morphogenetic movements, summary of, 

 during gastrulation, in frog and 

 other amphibia, 415 

 Mossman, H. W., 910, 915, 920 

 Motor fiber, 816 



Motor nucleus, dorsal, of vagus nerve, 831 

 Motor plate, 838 

 Mouse, placentation in, 915 

 Mouth, formation of, in Amphio.xus em- 

 bryo, 502 

 Mucosal walls, characteristics of, 620 

 Mucous layer, of stomach, characteristics 



of, 620 

 Miillerian duct, 799 

 Muscle(s). 701 



abductor caudae externus. 716 

 abductor caudae internus, 716 

 adaptations of, aerial, 708 

 natatorial, 706 

 terrestrial, 706 

 adductor mandibulae, 717 

 arrector pili, attached to hair follicle, 581 

 result of adrenaline stimulation on, 

 882 

 associated with hyoid visceral arch, de- 

 velopment of. 717 

 associated with mandibular visceral arch, 



development of, 717 

 associated with spinal accessory nerve, 



development of, 718 

 branchial, development of in various 



vertebrates, 708, 718 

 cardiac, characteristics of, 700, 701 



histogenesis of, 702 

 ciliary, origin of, 853 

 coccygeo-iliacus, of frog, 707 

 coccygeo-sacralis, of frog, 707 

 depressor mandibulae. of birds, 718 



of frog, 717 

 derived from posterior visceral arches, 



development of, 718 

 digastric, 717 



dorsalis trunci, of Nectiirus, 101 

 extrinsic, of eye, 716 



innervation of, 716 

 facial and cervical, derived from meso- 

 derm of hyoid arch, 779 

 first ventral constrictor muscle shark, 



717 

 iliocostalis, of human embryo, 714 

 iliopsoas in human, 715 

 intercostales externi, of human embryo, 



715 

 intercostales interni, of human embryo, 



715 

 interneurales, of frog, 707 

 interspinales, in human embryo, 714 



