476 



INDEX 



Oil, Olive, 169, 170, 171. 

 Oily seeds, transformation of food in, 314, 

 Oleander, protection of , against drying, 215. 

 333, 337.* 



transpiration of, 204. 

 Olive oil. See Oil, Olive. 

 Onion, germination of, 47, 72, 81. 



pollen of, 293. 



roots of, 86. 



storage of food in, 313. 

 Opening and closing of flowers. See Flower. 

 Opium Poppy. See Poppy, Opium. 

 Opuntia. See Prickly Pear. 

 Orange rays cut out by cupra-ammonia, 265. 

 Orchids, cross-pollination of, 306, 307. 

 Orchis. See Orchids. 

 Oriental Poppy. See Poppy, Oriental. 

 Origin of species, 441-453. 

 Osmosis, 122, 123,* 124. 



generates pressure, 60, 61,* 62.* 



in seed, 60, 63, 64, 67. 



makes stem rigid, 269. 



of leaves, 242. 



relation of, to growth, 64-68. 



through seed-cover, 16,* 17, 18, 19,* 20. 

 Osmotic pressure, measurement of, 62,* 63. 

 Ovary, 288,* 289, 290.* 



correlation of, 360. 

 Ovule, 288,* 312. 

 Oxalate of ammonium. See Ammonium 



oxalate. 



Oxalate of lime. See Lime oxalate. 

 Oxalic acid. See Acid, Oxalic. 

 Oxalis, dispersal of seeds of, 321. 



opening and closing of flowers of, 295. 



protection of, against water, 214. 



sleep position of leaf of, 218. 

 Oxbows, experimental formation of, 111. 

 Oxidation, as source of energy, 35, 173. 



brought about by ferments, 173. 



See, also, Combustion and Respiration. 

 Oxygen, absorption of, 33, 34,* 35, 36, 175, 

 194, 195, 200, 287, 317, 388, 390. 



given off by leaf, 191,* 192,* 193,* 194, 195. 



how supplied to organisms, 176. 



needed for growth, 5,* 6, 32, 33,* 34,* 35, 

 36, 37,* 38, 39.* 40. 125. 126. 281.* 283, 

 326. 



See, also, Air. 



Papaver. See Poppy. 



Palisade cells, 198,* 199,* 200, 201. 



effect of light on, 345. 



poorly developed in water-plants, 339. 

 Palms, pollen of, carried by wind, 300. 

 Pancreas, 169. 

 Pancreatic juice, 169-172. 

 Pansy hybrids, 428. 

 Parasitic bacteria, 380. 

 Parenchyma of wounds, 319. 



See, also, Cell parenchyma, Bast paren- 

 chyma and Wood parenchyma. 

 Parental characters. See Heredity. 

 Paris, plaster of. See Lime sulphate. 

 Parsley family, flowers of, 298. 

 Parsnip, flowers of, attract bees, 299. 



storage of food in, 313. 



sugar in, 122. 

 Partridge -berry, cross -pollination of, 304, 



305.* 



Passiflora. See Passion Flower. 

 Passion Flower, 272. 



calyx of, 288. 



Pasteur's solution, formula of, 398. 

 Pasteurization of milk, 377. 

 Pastinaca. See Parsley. 

 Pastures, remain in good tilth, 129. 

 Paving, keeps air from roots, 126. 

 Pea, 89, 141-144. 



absorption of water by seed of, 7. 



contains no pepsin, 172. 



cross-pollination of, 306. 



flower of, opened by bees, 308. 

 platform of, 307. 



food in, 177. 



germination of, 47. 



leaves of, follow sun, 218. 



pocket of seed of, 20. 



protection of fruit of, 320. 

 Pea, Sweet, pollen of, 292, 293. 

 Pea family, cross-pollination in, 303. 



dispersal of seeds in, 321. 



protection of pollen in, 294. 



root-tubercles of, 149, 384. 385. 



tendrils of, 272. 

 Peabody, on foods, 173. 

 Peach, escape from seed-cover of, 54. 



protection of, against drying, 214, 317. 



fruit of, 320. 



