INDEX 



425 



Vertebral eoliunn, 90 



divisions of, 91 

 Vertebrata, 278-280 



evolution of, 335 

 Vesalius, Andreas, 7, 8 

 Villus, 106, 107 

 Viscosity, changes in, 45 

 Visual purple, 1 10 

 Vitamin K, 130 

 Vitamins, 109-112 

 Viviparous, 183, 184, 185 

 Voluntary muscle, 96 

 Vol vox, gametes in, 161, 162 



sterile cells in, 70, 71-73, 75 



Wastes, water, 134 

 Wat(>r of protoplasm, 39, 40 

 White corpuscles, 126, 127 

 \\'liole, relation of, to parts, 64, 65 



X 



X body, Sagitta, 202 



X chromosome, 233, 234, 235 



Xenophanes, 2 



Xerophthalmia, 110 



X rays, as cause of mutation, 357 



Y 



W 



Wallaby, pouch of, 189 



Wallace, Alfred Russel, natural-selection 



doctrine of, 361 

 Wastes, defined, 133 



gaseous, 133 



origin of, 133 



Y chromosonic. 234, 235 



Z 



Zoogeography. 22, 307-324 

 major realms in. 323, 324 

 Zygapophyses, 91 

 Zygote, 159, 173 



