INDEX 



445 



natural selection, Charles Darwin on, 



385388, 392. 

 ,, ,, Erasmus Darwin 



on, 373. 

 ,, ,, insufficiency of, 



404. 



,, ,, insufficiency of, 



Charles Darwin 

 on, 392. 

 summary of theory, 



391. ' 



,, system, 226. 

 nectaries, 359, 360, 414, 415. 

 Neoceratodus, 255, 291, Fig. 110. 

 Neohipparion, 310, Fig. 157. 

 Nepenthes, 262. 

 Nerocila, 227. 

 nerve-cells, 58, Figs. 23, 24. 



,, fibres, 58. 

 nerves, 59. 



nervous system, 18, 121, 266. 

 neurons, 58, 59. 



neuter insects and heredity, 189, 190. 

 newts, 294. 

 New Zealand, fauna and flora, 258, 



328, 329, 331. 

 nipples, vestigial, 345. 

 nitrifying bacteria, 218. 

 Nitrobacter, 218. 

 Nitrosornonas, 218, Fig. 84. 

 nomenclature, 226, 227. 

 non-adaptive characters, 419 422. 

 normal curve of variation, 153. 



variations, 150. 

 notochord, 266. 

 Notornis, 397. 

 Notoryctes, 253. 

 nucellus, 108. 

 nuclear membrane, 69. 

 nucleinic acid, 71. 

 nucleolus, 70, 77. 

 nucleoplasin, 14, 22, 69. 

 nucleus, 13, 69. 



,, division (see mitosis and 

 amitotic nuclear division), 

 in heredity, 161, 166, 174. 

 zygote, 83. 



numerical variations, 149. 

 nutrition, 7 (see also food materials). 

 of embryo in Ccelomata, 

 125. " 



O. 



OBELIA, 119, 265, Fig. 60. 



ocean, age of, 287. 



oceanic islands, fauna, 330, 332, 397. 



oceans, permanence, 329. 



CEnothera, mutntion in, 155. 



oil-foam, 19, 21. 



Olenus cataractes, Fig. 134. 



Oligocene Epoch, 284. 



ontogenetic record, obscuring of, 



267, 278. 

 ontogeny, 263. 



,, abbreviation of, 273. 



a habit, 192. 



and phylogeny, 265, 279, 



Fig. 131. 

 Erasmus Darwin on, 371, 



372. 



,, interpretation of, 277. 

 Onychophora, distribution, 330. 

 oocytes, 133. 

 oogenesis, 133, Fig. 65. 

 oogonia, of Fucus, 1 00. 



in oogenesis, 133. 

 oospheres, 90, 100, 104, 108. 

 ooze, 26, 283. 

 opal, 24, 26. 

 Ophisaurus, 250. 

 Ophiura ciliaris, Fig. 126. 

 ophiuroids, 275, 276. 

 opossums, 301. 



opposable great toe and thumb, 424. 

 orang, brain, 425. 

 " orang utan," Buffon on, 370. 

 Orchidaceue, fertilization, 359362. 

 Orchis mascula, fertilization, 359 



362, Fig. 182. 

 orders, 226. 



Ordovician Epoch, 284. 

 organellse, 39. 

 organic evolution, doctrine of, 212 



(see also evolution). 

 units, 38, 65. 

 organism, 3. 



organisms, first appearance of, 212. 

 nature of first, 217, 219. 

 number and variety of, 



211. 



origin of, 214216. 

 organizing spirits, A. E. Wallace on, 



394. 



organs, 12, 38. 



origin of great groups, 303, 304. 

 living things, 214 216. 

 sex, 84, 85, 89, 126128. 

 Ornithorhynchus, 234, 260, 301, 



Fig. 91. 



Ornithosauria, 299. 

 Ornithoscelida, 297. 

 Orohippus, 310, Figs. 153, 155. 

 Osborn, 369. 

 osmosis, 8, 17, 23. 



