INDEX 



479 



Poplar, transpiration of, 204. 

 Poplar, White, hairy covering, 213. 

 Poppy, needs light for germination, 47. 



position of Howers of, 307. 



protection of, against animals, 222. 

 Poppy. Opium, 427,* 428. 

 Poppy, Oriental, 427,* 428. 

 Poppy hybrids, 427-429 * 

 Portulaca. See Purslane. 

 Potamogeton. See Pondweed. 

 Potash, as plant-food, 139, 140.* 



how supplied to soil, 152. 



increases fruit production, 318. 



needed by plants, 139, 140,* 



set free by lime, 1.32. 

 Potassium, bichromate, as light filter, 265. 



chlorate, 235. 



nitrate, 139, 148, 153. 



permanganate, 364. 

 Potato, correlation in, 360. 



cuticle of, 328. 



effect of freezing on, 353. 



light on, 327, 328.* 



water on, 326, 327,* 328,* 329, 330. 



eyes of, 260. 



for bacterial cultures, 365.* ;J66, ;;67,* liSO. 



protection of pollen by, 295. 



starch in, 328. 



stem nature of tuber of. 260. 



storage of food by, 260, 297, ;u:;. 



transpiration of, 328. 

 Potato, Sweet, twining of, 275. 

 Potato Vine, tendrils of, 270. 

 Potentilla. See Cinquefoil. 

 Powell, on pruning, 264. 

 Preservation of foods, 376, 377, 385-388, 397. 

 Prickles, effect of light on, 347. 



protect against animals, 221. 

 Pricldy Lettuce. See Lettuce, Prickly. 

 Prickly Pear. See Pear, Prickly, 

 Primrose, cross -pollination of, 305. 



protection of pollen by, 294. 

 Primrose, Evening, Broad, 446,* 447.* ' 



— Dwarf. 445.* 



— Lamarck's, mutations of, 443, 444,* 



445,* 446, 447.* 



— Pale, 447.* 

 Primula. See Primrose. 

 Propagation. See Reproduction. 



Protection against animals, etc., by bark, 

 2.i6. 

 bitter taste, 222, 260, 320. 



— — — — concealment, 260, 320. 

 hairs. 221, 256, 260. 



— — — — hugging the ground, 22:J. 

 — hard coverings, 320. 



— — — — poisonous substances, 162, 222. 

 prickles, 221. 



— spines. 221, 256, 260, 320, ;j;U * 



334. 



suspension, 320. 



teeth of leaf, 222, 334. 



texture, 223. 



thorns, 221, 260. 



— cold, 353, 354. 



— drying by calyx, 288. 



— — — dispensing with leaves, 215, 331,* 



332,* 343.* 



enwrapping leaves, 251, 261. 



hairy coverings, 213, 333, 334,* 



335.* 



— ~ — position of leaves, 217, 218.* 



— — — reduction of leaf - surface, 21."', 



333. 342.* 



— — — — — number of stomata, 21.'i, 



335, 336.* 

 rolling and folding of leaf, 213, 



334. 



sinkingof stomata, 215, 335,337.* 



storage of water, 331,* 334. 



thicker cuticle. 333, 334,* 337,* 



338.* 



— — — water-proof substances, 214, 251, 



333, 334.* 



— — — water-retaining substances, 216. 



— — — woody coverings, 317. 



— dust by hairs, 214. 



— fire by bark, 256. 



— fungi by bark, 256. 

 callus, 263. 



— water by callus, 263. 



hairs, etc., 214. 



— wax, 214. 



of plumule, 71,* 72,* 79.* 



— root, 161, 162. 

 Proteids, decomposition of, 381. 



energy from, 173, 174. 

 formatiou of. 201, 253, 254. 



