INDEX 
Unit characters, 98; misplaced, 138; 
species composed of, 98 
Unused materials, 30 
Urus, 22 
Variability, coefficient of, 112; eco- 
nomic significance of, 44; from 
type, 109; in a single character, 47; 
in milk production, 40; in pigeons, 
93-95; of a single character, 105 
Variation of domesticated races, I1 
Vetch, 264 
Vigor, significance of, 69 
Wart hog, 233 
Way of the wild, 50 
Weapons, defensive, significance of, 71 
Weeds, 298 
Weeping habit, 151 
Wheat of lake dwellers, 265; ori- 
gin of, 242; strains of, 243 
Wild ass, 22 
Wild boar, 16, 231 
Wild grape, 15* 
Wild lettuce, 299 
Wild white cattle, 225 
Wolf, contrasted with dog, 22; domes- 
tication of, 13%, 21; of South Amer- 
ica, 208 
Women, primitive, hard lot of, 2 
Yak, 221° 
Zebra, 217 
