200 INDEX 



villi, 58 



Pleistocene, 8, 10, 17, 22, 36 

 Plica semilunaris, 73 

 Pliocene, 16 

 Polydactylism, 55 

 Pomace fly, 155 

 Population, and subsistence, 178 



effect, of the world, 178 



foreign-born birth-rate, 174 



limits of, 178-179 



maximum, 178 



native birth-rate, 174 



negro, of United States, 176 



South American countries, 176 



United States, 178 

 Postnatal retardation, 68 

 Prepubertal acceleration, 69 

 Primary germ layers, 43 

 Primates, intelligence of, 111 

 Primitive streak, 43 

 Processes, rational, 111 



selective, 143 

 Products, cultural, 134 

 Progress and evolution, 127 



due to specialization and coopera- 

 tion, 160 



definition of, 159-160 



limits of, 160-161 

 Propagation, by selection, 170 

 Proportions of body, changes in during 



life, 65 



Protestantism, 144 

 Protoplasm, primeval, 152 

 Protozoa, 39 

 Puberty, 69 



influenced by internal secretion, 69 

 Pygmies, 5 



Race, composite, characteristics of, 177 

 differentiation and amalgamation, 



174-178 

 mixtures, 175 



Race suicide, 135 

 Roman Empire, 180 



Races, blending of, 176 



difference in intelligence, 115 



primary, of mankind, 176 

 Racial isolation, 174 

 Rational, conduct, 105 



processes, 111 

 Reactions, adaptive, 113 



animal, acquiring of, 121 



reflex, 106 



spontaneous, 107 



summary of, in various animals, 111 



tropistic, 113 

 Realm, societal, elemental forces in, 



149 



Reason and instinct, 105 

 Recapitulation, Law of, 52 

 Receptors, 85 



sea-anemone, 89 

 Recombinations, 154 

 Reflex actions, 106 



theory of the origin of, 107 

 Regeneration, in amphibia, 65 



in man, 65 



power of, 65 

 Rejuvenescence, 71 

 Religion, 136, 147 



evolution of, 123 



Reproductive system, development, 53 

 Retardation, postnatal, 68 

 Retrogression, 73-75 

 Rhodesia, Broken Hill mine, 12 

 Rhodesian man, 28-31 



skull, 30 



Ribs, variation in number, 75 

 Roman Empire, race suicide, 180 

 Rome, decay of, 179 

 Rubner, 72 

 Rutot, A., 4 



Schoetensack, Dr. O., 16, 19 

 Science and religion, 144 

 Sea-anemone, creeping, 88 



effect of stimulation, 86 



effectors, 89 



