Vibrion, septic, 193 Vis viva, 73 Vital properties, theory of, 29 _et seq._ Vitalism, 6, 7, Chap. iii. _passim_; physico-chemical, 29 Vitality, phenomena of, 216 Vortex, vital, 105, 120, 229 _et seq._ Vulcans, 26-7 Weight, energy of position, 64; conservation of, 65; movement under action of, 271 _et seq._ Work, 70, 72; and force, 74, 77; converted into heat, 92; physiological, 103 Xanthic bases, 180 Zones, metastable and labile, 301 THE WALTER SCOTT PUBLISHING COMPANY, LTD., FELLING-ON-TYNE.