Vision, continued. 



double, 667. 



duration of sensation in, 660, 

 estimation of the form of objects, 



657. 



of their motion, 658. 

 of their size, 655. 

 field of, size of, ib. 

 focal distance of, 650. 

 impaired by lesion of fifth nerve, 



547, 548. 



influence of attention on, 659. 

 modified by different parts of the 



retina, 663. 



organ of, 637. See Eye. 

 phenomena of, 646. 

 in quadrupeds, 668. 

 single;, with two eyes, 665. 



its cause, 668-72. 

 structures essential for, 646. 

 Visual direction, 657. 

 Vital capacity of chest, 212. 



motions, 579. 

 Vitality. See Life. 



dormant, 4, 12. 

 Vitelline duct, 746. 

 membrane, 720, 741. 

 spheres, 741. 



Vitellus, or yelk, 721. See Yelk. 

 Vitreous humour, 645. 

 Vocal cords, 



action of in respiration, 210, 233. 

 approximation of, effect on height 



of note, 613. 

 attachment of, 609. 

 elastic tissue in, 46. 

 longer in males than in females, 6 1 6. 

 position of, how modified, 611. 

 vibrations of, cause voice, 605, 619. 

 Voice, 605. 

 of boys, 6 1 6. 

 compass of, 615. 



conditions on which strength de- 

 pends, 619. 

 human, produced by vibration of 



vocal cords, 605, 619. 

 impaired by destruction of ac- 

 cessory nerve, 565. 

 in eunuchs, 617. 

 influence of age on, 616. 



of arches of palate and uvula, 



619. 



of epiglottis, 613. 

 of sex, 615. 



INDEX. 825 



Voice, continued. 



influence of ventricles of larynx, 



620. 

 of vocal cords, 605, 6n. 



in male and female, 615. 

 cause of different pitch, 616. 



modulations of, 6 1 8. 



natural and falsetto, ib. 



peculiar characters of, 617. 



varieties of, 615. 

 Volatile bodies, influence of on sense 



of smell, 634. 



Voluntary muscles. See Muscles. 

 Vomiting, 



action of stomach in, 296. 



mechanism of, 233. 



influence of spinal cord in, 506. 



voluntary and acquired, 297. 

 Vowels and consonants, 620. 

 Vulvo- vaginal glands, 719. 



W. 



Walking,muscular action in, 599, 602. 

 W arm-blooded animals, 244. 

 Water, 



absorbed by skin, 439. 



by stomach, 288. 

 in blood, variations in, 88. 

 conduction of sound through, 684. 

 deficient in thirst, 93. 

 exhaled from lungs, 227, 437. 



from skin, 436. 



forms large part of humanbody, 26. 

 influence of on coagulation of 



blood, 75, 76. 

 on decomposition, 1 8. 

 in urine, excretion of, 448. 



variations in, 454. 

 vapour of in atmosphere, 220. 

 "Wave of blood in the pulse, 160. 

 Weight, relation to capacity of chest, 



213; 



sensation of, 711. 



White corpuscles. See Blood-cor- 

 puscles, white; and Lymph-cor- 

 puscles. 



fibro-cartilage, 50, 53. 

 White substance of nerve-fibre, 468. 

 Will, 



reflex actions amenable to, 506-8. 



transmission of through cord, 500. 

 Willis, circle of, 191. 

 Wolffian bodies, 779. 



