Animals, coloration of, 126, 127. Animals, death rate of, 123. Animals, grass-eating, 137. Animals, gregarious, 150. Animals, multicellular, 4, 229. Animals, multiplication of, 122. Animals, snake-eating, 136. Animals, segmented, 233, 234. Animals, unicellular, 4, 229. Animals, unsegmented, 233. Annulata, 233. Ant-bear, 123. Antelope, desert, 127. Antitoxines, 15. Anthropoid Apes, 243. Anthropoid Characters, 185. Anthropomorphism, 211. Anthropopithecus, 243, 244. Anthropoidea, 240, 241. Antlers, of deer, 14, 157. Ants, 110, 123, 233. Anura, 238. Apes, anthropoid, 243. Arachnida, 233. Arcella, 16, 231. Archæan land, Canadian, 86. Archæan land, Blue Ridge, 86. Archæan land, Rocky Mountain, 86. Archæopteryx, 108, 238. Archegosaurus, 103, 238. Arctic regions, 151. Argonaut, 98. Armadillos, 114. Arthropoda, 233. Arthropods, 96, 98, 99. Artificial Selection, 120, 121, 122. Asteroidea, 232. Atavism, 51, 52, 191. Ateles, 242. Attraction-sphere, 27. Aves, 234, 238. Aye-Ayes, 241. Baboons, 243. Baby, grasping power of, 192. Bach, family of, 40. Bacillus diphtheriæ, 16. Bacillus, tetanus, 15. Bacteria, 14. Bacteria, nitrifying, 16. Badger, 123. Balanoglossus, 233. Barriers, geographical, 166, 169. Barriers, sexual, 166, 169. Bat, 127, 130. Bear, polar, 127. Beavers, 157. Bees, 59, 60, 102, 105, 110, 123, 163, 164. Bee-eaters, 127. Beetles, 147. Belemnites, 108. Berg adder, 149. Biophors, 6. Bipes, 115. Blastids, 99. Blastoidea, 233. Blastula, 32. Bird fancier, 120. Birds, 96, 105, 107, 109, 144, 146, 147, 148, 152, 159. Birds, courtship of, 153, 154. Birds, eggs of, 132, 133, 134, 135. Birds, excreta of, 142. Birds, humming, 152, 157, 159. Birds, paradise, 152. Birds, reptilian, 108. Birds, singing of, 154, 155. Birds, snake-eating, 147, 149. Boar, wild, 121, 157. Body-cells, 45, 64. Borneo, 138. Bower birds, 155. Brachiopoda, 232. Brachiopods, 96, 97, 100, 102, 105. Brain, 232, 233, 234, 235, 239. Brain, development of, 199, 214, 215. Brain, fœtal, 203, 204. Brain, ideal section of, 203. Brain, of fish, 199. Brain, of lemur, 201. Brain, of man, 203, 206, 211. Brain, of marsupial, 200. Brain, mind immanent in, 208. Brain, of monkeys, 202. Brain, psychic phenomena of, 206. Brain, of reptile, 199. Bryophyta, 244. Bryozoa, 232. Bull, 157. Bullfinch, 154. Butterflies, 59, 102, 110, 135, 139, 140, 141, 142, 143, 145, 147, 148, 158, 233. Bulldog, 121. Caducibranchiata, 178, 237. Calamoichthys, 236. Callithrix, 242. Camel, 127. Canaries, 154. Carinatæ, 238. Carnivora, 239. Carus, Dr. Paul, 208. Castration, 224. Catarrhinæ, 241. Caterpillar, 135, 138, 139, 140, 141, 145. Cats, forest, 128. Cattle, 169.