1340 



INDEX. 



Urobilin, 519 



Use, muscle substance increased by, 128; 

 skilled movements facilitated by, 779 



" Uterine milk," 1122, 1129 



Uterus, the, reception of the ovum by, 

 1111; changes in mucous membrane 

 of, during menstruation, 1112 ; changes 

 after impregnation, 1119; expansion 

 of, during pregnancy, 1136 ; "retrac- 

 tion" of, 1137, 1139; rhythmical con- 

 tractions of, during pregnancy, 1136; 

 during ' labour,' 1137 ; nerves of, 1141 



Utricle, primordial, 4 ; of labyrinth, 1009 



Vagus, see Nerves, vagus 



Valves of the veins, 171 



of the heart, their action in circula- 

 tion, 182-185 ; sounds caused by their 

 closure, 189, 190; tricuspid, their 

 action, 183 ; semilunar, of the pulmon- 

 ary artery, 185; their action, 186; 

 semilunar, of aorta, 189, 207; Eusta- 

 chian, 182 



, ileo-caecal, mechanism of, 381; of 



the lymphatic vessels, 404 



Vapour, aqueous, in expired air, 440 



Vascular mechanism, 149-307 ; main fea- 

 tures of the apparatus, 150 ; main regu- 

 lators of, apparatus, 238, 244, 262 



walls, their action on the blood, 27; 



alteration of, in inflammation, 293, 294 



Vas deferens, contraction of in emission, 

 1117 



Vaso-motor action, 262-288 ; arterial tone 

 due to, 264 ; effects of, 275 ; cutaneous 

 and splanchnic, compensatory, 305; 

 compensatory in loss and increase of 

 blood, 296 ; summary of, 284 ; its rhyth- 

 mic tendency, 507 ; regulation of tem- 

 perature by, 642 



centre, 280-284; limits of , 283 ; re- 

 lations of, to other centres, 284 

 - fibres, constrictor, 266-269, 272; 

 course of, 273, 278, 284 ; loss of medulla 

 in, 274, 285; tonic action of, 275-283; 

 chief parts of body supplied by, 278 ; 

 dilator, 269; course of, 275; usually 

 employed in reflex action, 278 ; reten- 

 tion of medulla in, 285 



functions of the central nervous 



system, 277; nerves of veins, 288 



Vegetable cell, storage of metabolic 

 products in, 654 



diet, results of, 664; large amount 



required, 6(56 



Veins, structure of, 152; minute, ib.; 

 their capacity as compared with ar- 

 teries, ib. ; walls of,i&. ; blood-pressure 

 in, 155, 159 ; valves of, 171 ; vaso-motor 

 nerves of, 288 



Velocity of nervous impulse, 72, 73; of 

 muscular contraction, 83, 84; compara- 



tive, of arterial, venous, and capillary 

 circulation, 161-171 ; of arterial current, 

 172; of flow in capillaries, 177; of flow 

 in veins, 176; of blood current, 229; of 

 pulse wave, ib. 



Venous circulation, aids to, 171; pulse, 

 236; sinuses of brain, 828 



Ventilation, positive and negative of 

 lung, 482 



Ventricle of heart of frog, its action in 

 heart-beat, 240-248; of tortoise, iso- 

 lated, spontaneous heart-beat of, 243 



Ventricles of the heart, synchronism of 

 their action, 182 ; their change of form 

 in cardiac cycle, 185; four stages of 

 action of, 212 ; tonic contraction of, 260 



Vertigo, causes of, 733 



Vesicles, cerebral, 835; optic, 835; otic, 

 980 



Vesiculse seminales, their action in emis- 

 sion, 1117 



Vestibule of ear, 980; parts of, 1008; 

 perilymph cavity of, 1013 



Vibrations of muscle sound, 122, 123; 

 sonorous, longitudinal and transversal, 

 990; of the tympanic membrane, 989; 

 through the auditory ossicles, 991; 

 through the bones of the skull, 993 

 of sound and light compared, 1000 



, interference of, 1005 



Vierordt, his hsematachometer, 173 



Vieussens, annulus of, 247, 253-256 



Villi, the, columnar epithelium of, 417; 

 pumping action t>f, 419; of chorion, 

 fretal, 1121 



Vision, 781; binocular, 782, 939-958; its 

 action in judging of distance, 964; in 

 judging of solidity, 966 ; mechanism of, 

 782; central apparatus for, 788 ; imper- 

 fections of, 790; dioptric mechanisms 

 of, 834, 839 ; astigmatism, 871 ; spherical 

 aberration, 871 ; entoptic phenomena, 

 874 ; distinct limits of, 887 ; trichromic 

 nature of, 898, 905; colour, Young- 

 Helmholtz's theory of, 898, 935 ; Bering's 

 theory of, 900, 935; field of, 782, 929, 

 940 ; corresponding or identical points, 

 942 ; struggle of the two fields of, 959, 

 968 



Visual areas in fovea centralis, 888 ; axis, 

 939; centres, lower, 793; impulses, 

 development of, 916; impulses, origin 

 of, 920; perceptions and judgments, 

 959 ; perceptions, psychical processes in, 

 961; plane, 940; purple, 922 



sensations, 781-794; probable mode 



of development of, 793 ; fusion of, 886, 

 887; in relation to visual perceptions, 

 929-938 ; simultaneous, 929 



units, retinal, 889 



Vitreous humour, the, 974 



Vocal cords, 1071 ; voice produced by the 



