SELECTION. 



INDEX. 



HYSTKM. 



429 



Selection of domestic products, 20, 



21. 

 , principle not of recent origin, 



23. 



, unconscious, 23. 



, natural, 57. 



, sexual, 64. 



, objections to term, 58. 



natural, has not induced steri- 

 lity, 231. 



Sexes, relations of, 64. 



Sexual characters variable, 115. 



selection, 64. 



Sheep, Merino, their selection, 21. 

 , two sub-breeds, unintention- 

 ally produced, 24, 25. 



, mountain varieties of, 55. 



Shells, colours of, 99. 

 hinges of, 144. 



littoral, seldom embedded, 253. 

 fresh -water, long retain the 



same forms, 289. 



, dispersal of, 323. 



of Madeira, 327. 



land, distribution of, 327. 



, resisting salt water, 331, 



332. 



Shrew-mouse, 350. 

 Silene, infertility of crosses, 227. 

 Silliman, Prof., on blind rat, 102. 

 Sirenia, their affinities, 283. 

 Sitaris, metamorphosis of, 371. 

 Skulls of young mammals, 148, 360. 

 Slave-making instinct, 202. 

 Smith, Col. Hamilton, on striped 



horses, 120. 

 , Mr. Fred., on slave -making 



ants, 202. 



, on neuter ants, 216. 



Smitt, Dr., on the Polyzoa, 180. 

 Snake with tooth for cutting through 



egg-shell, 200. 

 Somerville, Lord, on selection of 



sheep, 21. 



Sorbus, grafts of, 230. 

 Sorex, 350. 



Spaniel, King Charles's breed, 24. 

 Specialisation of organs, 91. 

 Species, polymorphic, 32. 

 , dominant, 40. 



, common, variable, 39. 



in large genera variable, 41. 



, groups of, suddenly appearing, 



264, 268. 



beneath Silurian formations, 



269. 



Species successively appearing, 272. 



changing simultaneously 



throughout the world, 279. 



Spencer, Lord, on increase in size of 

 cattle, 24. 



, Herbert, Mr., on the first steps 



in differentiation, 93. 



, on the tendency to an equili- 

 brium in all forces, 236. 



Sphex, parasitic, 202. 



Spiders, development of, 366. 



Sports in plants, 7. 



Sprengel, C. C., on crossing, 70. 



, on ray-florets, 108. 



Squalodon, 283. 



Squirrels, gradations in structure, 

 129, 130. 



Staffordshire, heath, changes in, 51. 



Stag-beetles, fighting, 64. 



Star-fishes, eyes of, 135. 



, their pedicellariae, 179. 



Sterility from changed conditions of 

 life, 7. 



of hybrids, 220. 



, laws of, 225. 



, causes of, 231. 



, from unfavourable conditions, 



234. 



not induced through natural 



selection, 231. 



St. Helena, productions of, 326. 



St. Hilaire, Aug., on variability of 



certain plants, 162, 163. 



, on classification, 345. 



St. John, Mr., on habita of cats, 



195. 



Sting of bee, 153. 



Stocks, aboriginal, of domestic ani- 

 mals, 13, 14. 



Strata, thickness of, in Britain, 251. 

 Stripes on horses, 120, 121. 

 Structure, degrees of utility of, 149. 

 Struggle for existence, 44. 

 Succession, geological, 272. 



of types in same areas, 291. 



Swallow, one species supplanting 



another, 55. 

 Swaysland, Mr., on earth adhering 



to the feet of migratory birds, 



308. 



Swifts, nests of, 213. 

 Swim-bladder, 138. 

 Switzerland, lake-habitations of, 12. 



13. 

 System, natural, 342. 



