INDEX 



211 



Skeletons of unicellular organisms, 32, 

 PL 21 ; of arm of vertebrates, 92. 



Skin muscles in man, 94. 



Skunk, 133, 134, PI- 12. 



Skunk-cabbage, 154. 



Slavonia, fossil Paludina, 107. 



Small pox, 171. 



Smelting ore, 176. 



Smerinthus tilice, PI. 55; ocellata, 142. 



Snail, development of pond, 97. 



Snails of Oahu, segregation, 63. 



Snakes, aggressive color, 126; behavior of 

 poisonous, 143; hind limbs, 93, 94; 

 mimicry, 139, PL 79; protective color, 



120. 



Snipe protective color, 119. 



Snow grouse seasonal color change, 121, 

 PL 57 . 



Snowy owl, 126. 



Socialism, control of marriage, 182; nature 

 socialistic, 187. 



Social progress, an end in itself, 176; 

 vs. evolution, 173-177. 



Soil, relation to segregation, 63. 



Solea concolor, 89, go y 91. 



Soma, distinguished from germ cells, 70; 

 relation to processes of reproduction, 74. 



Sparrow, aggressive color, 126; protective 

 color, 1 1 8, PI. 49. 



Spathura solstitialis, PI. 26. 



Species, mean, 19 ; meaning of, 88 ; preser- 

 vation of species, not of individual, 

 secured by natural selection, 187. 



Spermophile, protective color, PL 53. 



Sphinx convolvuli, PI. 55. 



Spiders, aggressive coloration, 126, PL 7$; 

 aggressive mimicry of ants, 145 ; ene- 

 mies of, 12 1 ; protective coloration, 120, 

 PI. 75, PI. 8$; protective resemblances, 

 124, PL 64; resembling bird excre- 

 ment, 127; sexual coloration, PL 85; 

 sexual selection, 50, PL 28. 



Spilomyia hamifera, PI. 74. 



Spinal column, curvature in man and apes, 

 1 66, PL 99. 



Spizella, pusilla, PL 49. 



Sports, 19, 39, 46. 



Sprouts, Brussels, PL 7. 



Squirrel, confusing coloration, 148. 



Stability of certain species, 9. 



Staghorn beetle, 51, PL 29. 



Starfish, birth-rate, 13, 17. 



Stearns, PI. 3. 



Sterility, domestic races not mutually 



sterile, 31; of crosses between certain 

 individuals, 66; of crosses between 

 species, 31; of hybrids, 31, 41; of 

 soma cells, 71; of worker bees, recently 

 acquired, 77; starting-point in forma- 

 tion of species, 32. 



Stick-like insects, 122, PL 61 ; spider, PL 64. 



Stridulating organs, 51, PL 29. 



Struggle for existence, 10-18; between near 

 relatives, 25 ; man, 169. 



Summary, of Part I, 82 ; of color in animals, 



151- 



Supernaturalism, Intro, ix, x. 

 Superstition, Intro, ix. 

 Survival of the fittest, 15, 18. 

 Swamping of varieties by cross-breeding, 



40-47. 



Swedish turnip, PL 7. 

 Synageles picata, PL 28. 



Tadpole, of salamander, 98. 



Tail, vestigial muscles in man, 165, PL 95. 



Taxonomy, 88. 



Teeth, deterioration of human, 170; man 



and gorilla, 164, PL 92. 

 Tegetmeier, PI. 12-15, P1 - l8 > P1 - J 9> P1 - 2 4- 

 Tendency, inherent, in evolution, 188; in 



variat'on, 40. 



Terrifying attitude, 139, 140, 142, PI. 78. 

 Tetragnatha gr dilator, 120; laboriosa, PL 85. 

 "Thierleben" (Brehm), 4, 22, 31, 133, PI. 



24, PL 30, PI. 33, PI. 62, PI. 99. 

 Thomisidce, 129. 

 Thompson, J. A., 189. 

 Thyroidopteryx ephemeriformis, 21. 

 Tiger, aggressive coloration, 129, PI. 68. 

 Timor, friar-bird and oriole, 144. 

 Timor Laut, friar-bird and oriole, 144. 

 Toad, aggressive coloration, 126, 133, 



PI. 66; rejects noxious insects, 130. 

 Tody, green, protective coloration, 119. 

 Tortoise, embryos, PL 38. 

 Trailing arbutus, odor, 154; variation, 7. 

 Transparency of pelagic animals, 117. 

 Tree-frogs, protective coloration, 125, PL 66. 

 Tree-hopper, mimicry of leaf-cutting ants, 



i37, PI- 75- 



Trends in evolution, 40, 188, 189, 192. 

 Trillium grandiflorum, PI. 2. 

 Triton cristatus, 52, PL Jj; punctatus, 52. 

 Trochilium apiforme, PL 7- 

 Tropidorhynchus, 144. 

 Tunicates, transparency of pelagic, 117. 

 Turkey cock, 49, PL 27. 



