976 



Sperm transport — (Continued) 

 in Chry semes picta female, 191 

 in external watery medium, 186 

 in forms where fertilization is internal, 



189 

 in hen, 191 



in Hydromantes genei female, 191 

 in Hydromantes italicus female, 191 

 in neotropical urodele, Oedipus female, 



191 

 in oviduct, influence of estrogenic hor- 

 mone on, 197 

 in rabbit, peculiar behavior of Fallopian 



(uterine) tube in, 193 

 in Salamandra atra female, 191 

 in Salamandra salamandra female, 191 

 muscular contractions as a means of, 193 

 outside of genital tract of male, 186 

 vas deferens as an organ of, 181 

 Spermatheca, 4, 189, 190 

 Spermatid, 125 

 Spermatocyte, definition of, 125 



maturation divisions in, as compared 

 with oocyte, 144 

 Spermatogenesis, and its stimulation by 

 FSHandLH (ICSH), 40-41 

 and mating urge, 22 

 in bat, Myotis, 23 

 in common fowl, 153 

 in common frog, Rana pipiens, 23 

 in deer. Odocoileus virginianus borealis, 



23 

 in garter snake, Thamnophis radix, 23 

 in ground squirrel. Citellus tridecemline- 



atus, 23 

 in the grasshopper, 131 

 later stages, of human, 148 

 seasonal, and accessory gland develop- 

 ment, 22 

 stages of. in guinea-pig, 148 

 Spermatogonia, 16, 17, 114 

 Spermatophore, 4, 18, 21, 189 

 Spermatozoa, 16, 21 



origin of term, 213 

 Spermia. 16. 21 



Spermiogenesis, comparison of in mammals 

 and insects, 154 

 definition of, 149 

 description of, 149 

 Sphaerodactylus notatus, xviii 

 Sphenodon, Tuatera, gastralia of. 697 



pineal organ of. 881 

 Spinal accessory nerve, 833 



muscles associated with, development of, 

 718 

 Spinal cord, as area of central nervous sys- 

 tem, 812 

 brachial enlargement of, 821 



Spinal cord — (Continued) 

 cavity of, 822 

 development of, 820 

 enveloping membranes of, 821 

 general structural features of, develop- 

 ment of, 818 

 Spinal ganglia, 812 

 Spinal nerve, component parts of, 826, 838 



formation of ventral root of, 819 

 Spiral folds (valves), of intestine, 632 

 Spiral ganglion, of acoustic nerve, 830 

 Spiral septum, 756 



Spiral valve (septum), of frog heart, 752 

 Splanchnic, definition of, 530 

 Splanchnic mesoderm, 506 

 Splanchnocoelic coelom, primitive, 858, 



659 

 Splanchnocranium, 668, 669, 679t 

 development of, 672 

 mammalian, developmental stages of, 



675 

 of frog, 677t 

 of human, 68 It 

 Splanchnopleure, definition of, 493, 530 



in yolk sac wall, 909 

 Spleen, 726, 766 

 Splenic corpuscles, 766 

 Sponges, gemmation in, 55 

 Spongioblasts, 810, 816 

 Spongy layer, of bird's egg, 906 

 Squalus, lateral line sensory cord of, 841 

 Squalus acanthias, dog fish, xvi 

 adult brain of. 832 

 alteration of primitive converging veins 



of heart of, 736 

 aortal vessel changes in embryo of, 760 

 characteristics of egg. site of fertilization, 

 and place of sperm entrance into 

 egg, 203t 

 coelom of, 858 

 developing skin of, 558 

 development of heart of, 728, 750 

 development of intestine in, 626 

 development of mesonephric duct in, 777 

 development of mesonephric kidney in, 



780 

 development of musculature of head of, 



717 

 development of olfactory organs of, 843 

 development of pancreas of, 628 

 development of reproductive ducts in, 



798 

 developmental stages of chondrocranium 



of, 669 

 early stages of tubulation of neural and 

 epidermal organ-forming areas, 

 475 

 external gill filaments of, 636, 638 



