202 



Stone, age of, 2 

 Sumner, W. G., 137, 139 

 Superstition, 163 

 Supracondylar foramen, 77 

 Survival of the fittest, 143 

 Sympathetic system, 85 



Tail, in man, 77 

 Tariff, protective, 128 

 Tasmanians, 3 

 Teeth, cynodont, 14 



decay, 75 



dentine, 57 



development, 57 



enamel, 57 



first set, 67 



fourth molar, 76 



Heidelberg man, 18 



permanent, 67 



pulp, 57 



retrogressive changes, 74 



taurodont, 14 

 Tendency, tropistic, 106 

 Tentacle, sea-anemone, 87 

 Tests, psychological, American Army, 



117 



Tetraprothomo, 10 

 Thames gravels, 35 

 Thymus glands, development, 49 



fate of, 50 



migration, 50 

 Thyroid glands, development, 49 



migration, 50 



Tools, not used by lower animals, 118 

 "Trial and error," 158 

 Transmission, of mores by tradition, 



141 



Transplantation, gonad, 96 

 Trinil, Java, 12, 13 

 Tropisms, 105, 106 

 Tubercle, Darwin's, of ear, 73 



Urinary system, development in rela- 

 tion to genital system, 53 



INDEX 



Uterus, contractions at birth, 60 



digestion of wall by embryonic cells, 

 58 



Variation, 130, 139 



accidental, in relation to reflexes, 

 107 



anatomical, 75-77 



and experimentation, 140 



and inheritance, 154-156 



and the world-code, 142 



depend upon verification, 140 



environmental, 154 



rational, 140 

 Vas defer ens, 71 



Vascular system, development, 51 

 Veins, development, 53 

 Ventricles, 51 



Vermiform appendix, 73, 74 

 Vertebral column, 44 

 Vestigial structures, 72-75 

 Villi, of placenta, 58 

 "Vital index," 174 

 Volition, 107 

 Volitional actions, 100 



War, and retrogressive selection, 168 



form of societal selection, 144 

 Water, 101 



currents, in sponges, 91 



percentage, in body, 64 

 Weight, average, 69 



increase in prenatal development, 63 

 Weismann, theory of, 71 

 West Indies, racial amalgamation in, 



176 



Woodward, Smith, 20, 30 

 World-code and variations, 142 



Yale Babylonian Collection, 2 

 Yolk sac, 43, 44 



"Zeros," 168 



