300 



INDEX 



Scorpions, the first . 32 

 Sea-birds colours of . 175 

 Secchi, Father, on atoms 227 

 Sensations . . . 208 

 Skull, changes in human 113 

 Snails, respiration of . 145 

 Solar-system, evolution of 



7 



Song in birds . . . 167 

 Sparrow's eggs, variation 



in .... 126 

 Speculation and observa- 

 tion . . . .197 

 Spencer, Herbert, "physio- 

 logical units "of .87 

 ,, on heredity and 



variation . . 100, 110 

 ,, on economy of 



growth . . . 112 

 ,, on natural selection 



146 



definition of life . 222 

 ,, on mineral colloids 235 

 ,, on abiogenesis . 235 

 Sperm-whale, loss of teeth 



in .... 147 

 Spiders, the first . . 46 

 Spirits, origin of belief 



in . . . .198 

 Sponges, the first . . 18 

 Sterility of hybrids . 160 

 Sympathy . . .208 

 Tabu, use of . . . 195 

 Theism . .201, 204, 279 

 Teleostomi . . .43 

 Thomson, H., on variation 



93 



"Time too short for develop- 

 ment . . . 141 



Tissue-mind and somatic- 

 mind . . . .119 

 Tradescantia, rotation of 



protoplasm in .92 



Trilobites, the first . 19 



,, use of spines of 25 



,, extinction of 35 



Tropical animals, bright 



colours of . . . 137 

 Tropical animals, numerous 



species of . . 185 



Tyndall, Prof., on life . 233 



Universe, evolution of . 3 



,, age of . .6 



Upland Goose of Patagonia 



146 



Use-inheritance . . 143 

 Useless characters . 150, 168 

 Utilitarianism . . 149 

 Variation, increase in rapi- 

 dity of . . 32, 135 

 Variation, definite and in- 

 definite . . 93, 97, 121 

 Variation, discontinuous 98 

 ,, causes of . 123 



,, in domesticated 

 animals . . . 127 

 Variations, incipient . 155 

 origin of mental 



208 



Vertebrata, the first . 27 

 Virchow, Dr., on civilisa- 

 tion . . . .67 

 Vital force . . .135 

 Vortex-ring hypothesis . 228 

 Veris, Dr., H. de, on 



"sports" ... 99 

 Wallace, A. R., on varia- 

 tion 93 



