GENERAL INDEX. 



553 



Vital capacity of the lungs, i. 427 



force, definition of, i. 25 

 Vitellin, composition of, i. 579 

 Vitelline membrane, absence of, in liuman ova, 



ii. 450 

 Vitreous humor, opacities in, ii. 321 



refractive index of, ii. 303 

 Vocal cords, false, ii. 422 



true, ii. 423 

 Voice, ii. 430 



changes at puberty in, ii. 489 



effect of age on, ii. 431 



pitch of. ii. 432 



registers of, ii. 432 

 Voice-production, ii. 421 



mechanism of, ii. 431 

 Voices, classification of, ii. 433 

 Volta, ii. 28 

 Voltaic pile, ii. 28 

 Voluntary control of the heart, i. 178 



muscular contractions, fatigue of, ii. 134 

 tetanic character of, ii. 133 



reactions, afferent paths of, ii. 226 

 anatomical mechanism of, ii. 226 

 compared with reflex, ii. 225 

 Vomiting, i. 387 



causes of, i. 388 



centre for, i. 389 



nervous mechanism of, i. 388 

 von Gudden's commissure, ii. 238 

 Vorticella, movements of, ii. 20 

 Vowel-sounds, ii. 431 



differences in quality of, ii. 385 



production of, ii. 434 

 Vulva, ii. 443, 462 



Walking, ii. 420 



Wallerian degeneration, changes of excitability 

 in, ii. 69 

 of nerve-fibres, ii. 197 

 of nerves, ii. 69 

 Wandering cells, definition of, i. 48 

 Water, absorption of, i. 313, 318 



amount lost through the lungs, i. 410 



distribution of, i. 503 



effect of, on pancreatic secretion, i. 236 



elimination of, i. 340 



imbibition of, i. 504 



Water, latent heat of, i. 504 

 nutritive value of. i. 27b', 354 

 percentage of, in brain and cord, ii. 274 

 properties of, i. 503 



pure, toxic action of, on nerves and muscles, 

 ii. 58 

 Weber's law, ii. 340 



applied to pressure-sensations, ii. 393 

 Weight of embryo, increase of, ii. 487 

 of the brain and spinal cord, ii. 274 

 decrease of. in old age, ii. 296 

 relation of, to social environment, ii. 277 

 of the child at birth, ii. 487 

 Weissinann's theory of heredity, ii. 502 

 Wharton's duct, i. 217 

 Whispering, ii. 436 



Whistling register of the voice, ii. 433 

 White matter of the central nervous system. 



water contents of, ii. 274 

 William's frog-heart apparatus, i. 188 



valve, i. 187 

 Wines, i. 535 

 Wirsung's duct. i. 231 

 Womb. See Uterus. 



Work done by contracting muscles, conditions 

 affecting, ii. 139 

 by muscular contraction, curve of, ii. 140 

 by the heart ventricles, i. 106, 107 

 Worms, segmental nervous system of, ii. 212 

 Wrisberg, cartilages of, ii. 422, 425 

 Wundt's tetanus, ii. 131 

 closing, ii. 37, 61 



Xanthin, i. 553 



of muscles, ii. 167 



physiological significance of, i. 339 

 Xantho-proteid reaction, i. 576 

 Xylose, i. 562 



Yawning, i. 454 



Young-Helmholtz theory of color vision, ii. 335 



Zollner's lines, ii. 351 

 Zona pellucida, ii. 454 



of the ovum, ii. 450 

 radiata of the ovum, ii. 449, 450 

 Zymogen granules, definition of, i. 228 



of the pancreas, i. 235 



