INDEX. 



655 



Veins, circulation in, 142 

 coats of, 141 

 of cranium, 151 

 effects of muscular pressure on, 



143 



of respiration on, 146 

 in erectile tissues, 152 

 foice of heart's action remaining 



in, 143 



influence of gravitation in, 142 

 muscular pressure in, 144, 145 

 rhythmical action in, 145 

 structure of, 141 

 systemic, 92 

 valves of, 142 

 velocity of blood in. 147 

 Velocity of blood in arteries, 147 

 in capillaries, 137 

 in veins, 147 

 of circulation, 147 

 of nervous force, 379 

 Vena portae, its arrangement, 89, 90, 



254 



Venous blood, characters of, 77-80 

 Ventilation, necessity of, 176 

 Ventricle, fourth, of brain, 404, 419 

 Ventricles of heart, 91 

 capacity of, 111 

 contraction of, 98 



effect on arteries, 



123, 127 



on circulation, 114 

 on veins, 143 

 force of, 110 

 development of, 599 

 dilatation of, 99 

 of larynx, office of, 486 

 Ventriloquism, 544 



mechanism of, 544 

 Vermicular movement of intestines, 



276 



Vermiform process, 414 

 Vertebrae, development of, 582, 594 

 Vesicle, germinal, 565 

 Graafian, 561, 563 



bursting of, 567-568 

 umbilical, 582 



Vesicles of vascular glands, 326 

 Vesicula germinativa, 565 

 Vesiculae seminales. 576 

 functions of, 576 

 reflex movements of, 399 

 Vesicular nervous substance, 375 

 Vestibule of the ear, 530 



of vagina, 562 

 Vibrations, conveyance of to auditory 



nerve. 536 

 perception of, 492 

 of vocal cords, 485 

 Vidian nerve, 433 

 Villi of intestines, 246 



Villi of intestines, action in digestion, 



270 



on intestinal glands, 241 

 Villi of chorion, 588 

 in placenta, 592 



Visceral arches, development of, 596 

 cavities, serous membranes of, 



315 



laminae, 582, 595 

 layer of pleura, 157, note. 

 Vision, 499 



angle of, 514 



at diiferent distances, adaptation 



of eye to, 510, 511 

 contrasted with touch, 515 

 corpora quadrigemina the princi- 

 pal nerve-centres of, 411 

 correction of aberration, 509, 510 



of inversion, 513 

 direction of, 515 



direction of rays in, how regu- 

 lated, 505 



distinctness of, how secured, 508 

 double, 523 



duration of sensation in, 517 

 estimation of the form of objects, 



515 



of their motion, 516 

 of their size, 513 

 field of, size of, 513 

 focal distance of, 510 

 impaired by lesion of fifth nerve, 



430, 431 



influence of attention on, 516 

 modified by different parts of the 



retina, 519 



organ of, 499. See Eye. 

 phenomena of, 506 

 in quadrupeds, 523 

 single, with two eyes, 521 



its cause, 524-526 

 structures essential for, 507 

 Visual direction, 515 

 Vital capacity of chest, 167 



motions, 454 

 Vitality. See Life. 

 Vitelline duct, 584 



membrane. 564, 579 

 spheres, 579 . 



Vitellus, or yelk, 564. See Yelk. 

 Vitreous humor, 506 

 Vocal cords, action of in respiration, 



166, 182 

 approximation of, effect on height 



of note, 481 

 attachment of, 478 

 elastic tissue in, 40 

 longer in males than in females, 



484 



position of, how modified, 481 

 vibrations of, cause voice, 475, 485 



