47o 



Index 



Silver-bill, 410. 



Sirex, 181. 



Siricidse, 181. 



Sitaria, 194. 



Skin, thickening of, 12, 13. 



Skull, 37, 65. 



Skunk, 3. 



Slaves of ants, 141. 



Sleep in plants, 404. . 



Sloth, 229. 



Snail, 417. 



Snails, color of, 23. 



Snakes, 14, 193-194, 227. 



Snowy owl, 6. 



Solenobia, 419. 



Soles, 137, 228. 



Sparassus, 178. 



Sparrow, 200; English, 112. 



Species, 31, 32, 33 ; adaptation for good of, 



19 ; sharp separation of, 131. 

 Spencer, 240-246, 247, 290. 

 Spermatozoa, 150, 430-433. 

 Sphinx, 186, 388. 



Spiders, 177-178, 179, 406; web, 3. 

 Spirogyra, 420. 

 Spontaneous variability, 134. 

 Spores, 322. 

 Squilla, 177. 

 Squirrels, 210. 

 Stag-beetle, 179. 

 Stags, 203-204, 219. 

 Sterility, 147-152. 

 Strasburger, 395. 

 Stridulating organs, 188, 189. 

 Struggle for existence, 109, no. 

 Stylonvchia, 442. 



Survival of the fittest, 107, 108, 109, 117. 

 Sutton, 432. 

 Swallow, 115. 

 Sweating, 12. 



Tadpole, 321, 428. 



Tail, 2. 



Tanager, 6. 



Tapeworm, 353; number of eggs, no. 



Taraxacum, 305. 



Tear-sacs, 206. 



Teeth, bird's, 67, 68. 



Telegony, 95, 234, 237, 238, 239. 



Tenthredinidse, 181, 425. 



Termite, number of eggs, no. 



Termitidse, 350. 



Thrush, 115. 



Tipulae, 188. 



Toad, 7. 



Torpedo, 132. 



Towle, 392. 



Transitional forms, 42. 



Transmutation theory, 31, 34. 



Traquair, 138. 



Treadwell, 72. 



Treat, 424. 



Tree-frogs, 7. 



Trichina, 353. 



Trifolium, 404. 



Triton, 193. 



Turkeys, 314. 



Turnix, 201, 202. 



Turtles, 193. 



Umbelliferse, 135. 

 Uria lacrymans, 124. 

 Utriculaiia, 10. 



Vanessa, 360. 



Variability, 92, 93, 95, 96, 318-319. 



Variation, 261, 340. 



Variation, fluctuating, 100, 118, 123. 



Variation under domestication, 136. 



Varieties, 106, 107, 148. 



Varigny, De, 303-306, 314-315, 322. 



Venus fly-trap, 9. 



Verbascum, 148, 149. 



Vertebrates, evolution of, 40, 45. 



Vilmorin, 303, 314. 



Vinson, 178. 



Vries, De, 97, 278, 289-298, 340. 



Vulpine, 209. 



Wallace, 7, 162, 186, 202, 221, 249. 



Walrus, 203. 



Walsh, 181. 



Walther, 59. 



Wasp, 3, 5, 408, 409. 



Waterton, 198. 



Web, spider's, 3, 4. 



Weir, 171. 



Weismann, 154-166, 441, 448-450. 



Westwood, 188. 



Whale, 227, 301. 



Wilson, E. B., 72. 



Wing of bat, 2. 



Wolf, 308, 376. 



Wolves, 412. 



Women, 210. 



Woodpecker, 228. 



Wounds, healing of, 15. 



Yarrell, 138. 

 Yung, 424, 436. 



Zebu cattle, 208. 

 Zeleny, 348. 

 Zoea, 69, 70. 



