408 



INDEX 



influence of, 106, etc. ; affects the 

 shape of animals, 107 ; effect of un- 

 favourable, 109. 



Erethism, definition of, 222. 



Evolution, factors of, 2 ; towards higher 

 complexity, 49, 265 ; necessity of long 

 periods for, 50, 69 ; method of, 130 ; 

 of nervous system, 311-312. See also 

 Inheritance of acquired characters. Dis- 

 use. 



Exciting cause of organic movements, 211 

 et seq. ; its components, 213 ; necessary 

 to life, 214. 



Eyes, of flat-fishes, 120. 



Family, definition of, 24. 



Fatigue, causes of, 348 ; effects of, 349. 



Feathers, origin of, from hair, 76. 



Feeling, organ of, as indicating natural 

 affinities, 31 ; not necessary to life, 

 208-209 ; as a faculty of animals, 273- 

 274 ; a function of the nervous system, 

 306, 322 ; a general effect, 321 ; due 

 to physical causes, 330. 



Fermentation, compared with life, 185- 

 186 ; 214. 



Fertilisation, nature of, 240 ; effects of, 

 276. 



Fishes, definition of, 79 ; primary division 

 of, 80 ; classification of, 156-161 ; 

 origin of, 176. 



Flying squirrels, their wings, 175. 



Fossils, explanation of, 46. 



Galeopithecus, 175. 



Gall and Spurzheim, on the functions of 



the brain, 285 ; criticism of, 368-369. 

 Galvanism, see Subtle fluids. 

 Genius, nature of, 390. 

 Genus, definition of, 25. 

 Geoffroy de St. Hilaire, his Egyptian 



collections, 41. 

 Giraffe, neck of, 122. 

 God, power of, 36, 41 ; purpose of, 180 ; 



methods of, 342. 

 Gordius, 176. 



Grasses, effect of environment on, 109. 

 Growth, peculiar to living bodies, 193, 

 261. 



Habit, nature of, 350. 



Heart, development of, 278. 



Heat, the first cause of life, 216 ; its 



effects on animals, 243-244 ; a material 



soul, 245. 

 Hemispheres, cerebral, see Hypocephalon. 

 Herbivores, size of, 121. 

 Hermaphrodites, characters of, 275. 

 Horns, origin of, 122. 

 Hypocephalon, the organ of intelligence. 



309 ; distinct from the brain, 363 ; 

 structure of, 367. 



Ideas, formation of, 371 ; two kinds of, 

 371 ; difference from sensation, 372 ; 

 production of, 373 ; physical nature of, 

 374-375 ; nature of complex, 375-376. 



Imagination, nature of, 388-391. 



Inflammation, due to concentration of 

 caloric, 213. 



Infusorians first established, 66 ; defini- 

 tion of, 102 ; arise by spontaneous 

 generation, 103 ; classification and list 

 of genera, 134-135 ; origin of animal 

 scale, 176 ; have no respiration, 269 ; 

 nutrition of, 345. 



Inheritance of acquired characters, first 

 and second law of, 113 ; in cultivated 

 plants, 109 ; in birds, 110 ; in dogs, 

 110; in horses, 113; factors of, 114; 

 accounts for webs of duck's feet, 119 ; 

 for legs of waders, 120 ; for long necks, 

 120 ; for long tongues, 120 ; for 

 asymmetrical eyes, 120 ; for the size of 

 herbivores, 121 ; for giraffes' necks, 

 122 ; for the claws of carnivores, 123 ; 

 for the shape of kangaroos, 123 ; in 

 sloths, 125 ; in seals and walruses, 174 ; 

 in flying squirrels and bats, 175 ; in 

 cetaceans, 178. See also Evolution, 

 Disuse. 



Innate ideas do not exist, 330, 364, 369- 

 370. 



Inner feeling, nature of, 333 ; functions of, 

 334 ; powers of, 336 ; the source of 

 movements, 339. 



Inorganic bodies, their origin, 51, 239, 

 258 ; comparison with living bodies, 

 191-194. 



Insects, definition of, 91 ; distinction 

 from arachnids, 90 ; degeneration of 

 wings among, 118 ; classification of, 

 141-146. 



Instinct, in animals, 350 : due to inherited 

 habits, 352-353, 364 ; a true guide, 359 ; 

 cp. with Season, 403. 



Intelligence, the highest animal faculty, 

 279 ; absent from invertebrates, 279 ; 

 connected with the hemispheres, 279 ; 

 disadvantages of, 361 ; variou.s kinds 

 of, 362 ; basis of, 363 : causes of, 364 ; 

 physical nature of, 377 : due to 

 nervous fluid, 378 ; based upon ideas, 

 378 ; principal function of, 379. 



Invertebrates, Lamarck's earliest classifica- 

 tion of, 64 ; general remarks on, 82. 



Irritability, the most general character- 

 istic of animals, 51 ; not found in 

 plants, 195 : nature of, 227-229 ; 

 different from sensibility, 228. 



