440 



INDEX, 



Species Hnccci'sivi-ly appearinjr, 205. 



clmn^'ini; riiinultaneously tliroii'^hout 

 the world, M-i. 

 Ppenccr, Lord, on increase in size of cat- 

 tle, 44. 

 Ucrbcrt. Mr., on the first steps indif- 



feri'ntialion, liO. 

 Mr. II., on tin? tendency to an equi- 

 librium in all forces, 252. 

 Sphex, parasitic, 212. 

 Spiders, development of. .3^7. 

 Spilz-doi; crossed with fox, 2o7. 

 Sports in plants, 25. 

 Sprengel, C. C, on crossing, 100. 



on ray-florets, 118. 

 Squirrels, sradafions in structure, 174. 

 Si;ifri)rdsliirc, heath, changes iu, 77. 

 Stag-beetles, fighting. 91. 

 Star-fishes, eyes of, 179. 

 Sterility from changed coaditions of life, 

 2i. 

 of hybrids, ?.3.3. 



' , laws of, 240. 



, causes of, 246. 



from unfavorable conditions, 251. 

 not induced through natural selec- 

 tion, 2ir,. 

 S;. Helena, productions of, 350. 

 St.-Ililaire, Aug., variability of certain 

 plants, i:50. 

 on classification, 377. 

 St. John, Mr., on habits of cats, 205. 

 Sting of bee, 197. 

 Slocks, aboriginal, of domestic animala, 



32. 

 Strata, thickness of. in Britain, 271. 

 Stripes on horses, 162. 

 Structure, degrees of utility of, 19 1. 

 Straggle for existence, 69. 

 Succession, geological, 295. 

 Succession of types in same areas, 316. 

 Swallow, one species supplanting an- 

 other, 81. 

 Swifts, nests of, 225. 

 Swim-bladder, 183. 

 Switzerland, lake habitations of, 31. 

 System, natural, 374. 



Tail of giraffe, 191. 



of atpuitic animals, 191. 



rudinientarv, 408. 

 Tanais, dimorpliic, 55. 

 Tarsi deliciciit. 1 li). 

 T.Miscli, on umlu'lliferjc, 129. 

 Tectli and l.nir correlated, 147. 



rudimentary, in embryonic calf, 406. 

 428. 

 Tciretmeier, Mr., on cells of bees, 219, 223. 

 Temminrk on distribution, aiding classi- 



llcation. 378. 

 Thompson, Sir W., on the age of the hab- 

 itable world, 272, 2tW. 

 Thoiiin, on grafts, 215. 

 Thrush, aquatic species of, 177. 



mocking, of the (}alai)agos, 366. 



young of. spotted, 395. 



nest of, 232. 

 Thuret, M., on crossed faci. 242. 

 Thwalles, Mr., on acclimatization, 144. 



Tierra del Fuego, dogs of, 207. 



plants of, .319. 

 Timber-drift, a33. 

 Time, lapse of, 268. 



by itself not causing modification, 10.5. 

 Titmouse, 176. 

 Toads on islands, 358. 

 Tobacco, crossed varieties of, 259. 

 Tomes, Mr., on the distribution of bats, 



360. 

 Torell. on a monocotyledonous Cambrian 



plant, 291. 

 Transitions in varieties rare, 168. 

 Trautschold, on intermediate varieties, 



279. 

 Trees on islands belonging to peculiar 

 orders, :J57. 



with separated sexes, 101. 

 Trifolium pratense, 79, 97. 



incamatum, 97. 



Trigonia, 302. 



Trilobites. 290. 



sudden extinction of. 302. 

 Triraorphism in plants, 55, 253. 

 Troglodytes, 232. 

 Tuco-tuco, blind, 141. 

 Tumbler, pigeons, habits of, hereditary, 

 207. 



young of, 400. 

 Turkey-cock, tuft of hair on breast, 92. 



nakotl skin on head, 192. 



young of, instinctively wild. 208. 

 Turnip and cabbage, analogous variationa 



of, 159. 

 Type, unity of, 200. 

 Types, succession of, in same areas, 316. 



Udders enlarged by use, 25. 



rudimentary, 405. 

 nex, young leaves of, 395. 

 Umbeilifene, flowers and seeds of, 129. 



outer and inner florets of, 148. 

 Unity of type, 200. 

 Uria lacrymans, 94. 

 Use, effects of. under domestication, 26. 



eflVcts of, iu a state of nature, 139. 

 Utility, how far important in the con- 

 struction of each part, 193. 



Valenciennes on fresh-water fish, 352. 

 Variability of mongrels and hybrids, 260. 

 Variation under domestication, 22. 



caused by reproductive system being 

 afTected by conditions of life, 23. 



under nature, 52. 



laws of, 137. 



correlated, 25. 1 16, 194. 

 Variations appear at corresponding ages, 

 27, 89. 



analogous in distinct speciea, 15S. 

 Varieties, natural, 52. 



struggle between, SO. 



domestic, extinction of, 109. 



transitional, rarity of, 168. 



when crossed, fertile, 257. 



when crossed, sterile, 256. 



classification of, 381. 

 Verbascum. sterility of. 2.37. 

 Vcrbascum, varieties of, crossed, 259. 



