INDEX 



477 



Peach, seed-cover of, 59. 



— — hinders absorption, 25. 



— path, of water in, 9, 24. 



sports of (Nectarine), 420. 

 Peanut, air-reservoir of, 42. 



buries its seeds, 70. 



protection of fruit of, 320. 



structure of fruit of, 3, 4.* 

 Pear, epidermis of fruit of, 317. 



hairy coveriDg of leaf of, 213. 



self -sterility of, 309. 



stomata of, 317. 

 Pear, Prickly, cross-pollination of, 306. 



effect of moisture and darkness on, 329. 

 Pearl ash, 154. 



Peat bogs, absorption difficult in, 217. 

 Peat moss, killed by lime, 350. 



loves sour humus, 351. 

 Pecan, escape from seed-covering of, 54. 



opening in seed-cover of, 8,* 9. 



path of water in seed-cover of, 9, 24. 

 Pectin compounds in fruits, 315. 

 Pelargonium, behavior of seeds of, 71. 



See Geranium. 

 Penicillium. 396, 397.* 

 Pepsin, 171. 172. 

 Peptone, 369. 



Perennials, flowering of, 286. 

 Periwinkle, leaf-arrangement of , 220,* 221.* 

 Petals, color of, 297-300. 



injury of, 288. 



transformed into leaf-like bodies, 359. 

 Petroselium. See Parsley. 

 Petunia, crossed with tobacco, 432. 

 Phaseolus. See Bean and Scarlet Runner. 

 Phleum. See Timothy. 

 Phoenix. See Date. 

 Phlox, protection of pollen of, 294. 

 Phosphoric acid. See Acid, Phosphoric. 

 Phosphorus, effect of, on production of 

 flowers and fruit, 318, 350. 



how supplied to soil, 150, 151. 



needed by plants, 139, 140.* 



obtained from bones, 150. 



test for. in soils, 155, 156. 



unites with starch in proteid formation, 

 254. 

 Photosynthesis. See Starch - foimation. 

 Phylloxera, 162. 



Physiography, experiments in, 103-lGO. 

 Picea. See Spruce. 

 Pinchot, on forestry, 245. 

 Pine, cambium of, 236,* 246. 

 correlation in, 3.59. 

 cross-pollination of, 302. 

 dispersal of seeds of, 321, 322. 

 latent buds of, 262. 

 pollen of, carried by wind, 300, 301. 



vesicles of, 301. 



protection of, against drying. 333. 334. 



fruit of, 320. 



wood of, compared with Oak wood, 235, 

 238. 



microscopic structure of, 235, 236.* 



Pine-apple, trypsin in, 172. 

 Pink Bean, See Bean, Pink. 

 Pink family, cross-pollination of, 303. 

 Pitcher Plant, pepsin in. 172. 

 Pith. 120,* 121, 269. 

 Pits. 227 * 229, 232,* 233, 234,* 235. 

 Plants, action of, in forming soil, 109. 

 alpine, 357, 358. 

 chemical action in, 166-177, 182-196, 253, 



254, 258, 259, 314-310. 

 climbing, 270, 271,* 272, 273,* 274, 275.* 

 decay of, 381. 

 dicotyledonous, 226. 



diseases of, 397, 398,* 399,* 400, 401, 402,* 

 403.* 404-407.* 408. 



damage done by, 400, 401, 406. 



prevention of, 400, 401, 407, 408, 440. 



engineering principles illustrated in struc- 

 ture of, 266. 267,* 268,* 269, 270. 

 form of, effect of correlation on, 359. 



fungi, on, 359. 



light on. 184,* 185, 261, 327, 



328,* 329,* 344,* 345*-348. 

 form of, effect of water on, 326,* 327,* 

 328,* 329,* 330, 331,* 332,* 333,* 334,* 

 335,* 336,* 337,* 338,* 339,* 340,* 341, 

 342,* 343,* 344.* 



effect of wind on, 348,* 349,* 350.* 



food of, in soil, amount of, 146. 



dissolved by carbonic acid. 



1?9-145. 



fixed by clay and humus, 145. 



set free by lime, 152. 



— needed by, 164-176. 



