6l2 



INDEX 



United States, immigration into, 

 526, 527 



population of, 535 

 Unity of the organism, 205 

 Urban environment, influence of, 



348-378 



Vaccination, against diseases, 438- 



441 

 Vascular system, integrative action 



of, 219-244 

 Venereal disease, 445 

 Venus, 14-16 



devoid of oxygen, 16 

 Vertebrates, evolution ot, 63 

 Vital index, of population, 528 

 Vital units, called cells, 187-204 

 Vitalism, 208 

 Vitamine C, 345 

 Vitamines, discovery of, 336 



properties of, 337-340 

 Vivisection, xiii, 434 



War, influence on birth-rate, 533 

 War-idea, 598 



Warm-blooded forms, evolution of, 71 

 Water content of blood, 227-229 

 Water supplies, 366-368 

 Weather, effects of, 295-330 



see climate 

 White races, characteristics of, 167- 



170, 173 

 White-Negro crosses, 556, 561 

 Woman, in primitive and advanced 



societies, 284-288 

 Women, and industrial life, 287 

 World, age of, 31 



definition of, 3 



population of, 517, 537 

 Worlds unknown, 29-31 



X-rays, discovery and use of, 441 



Yellow-brown races, characteristics 

 of, 167-170, 172, 174 



Paul B. Hoeber, Inc., 76 Fifth Avenue, New York 



