INDEX 
Parmelia, 79. 
Parthenogenesis, 40, 64, 169, 275. 
Peach curl, 71. 
Pecopteris, seeds, 183. 
Pediastrum, 21, 22. 
Pelargonium, capitate hairs, 337. 
Pellia, thallus, 101. 
Pellionia, starch grains, 389. 
Penicillium, 74. 
Pentacyclic flowers, 281. 
Peony, flower, 252. 
Perceptive region, 430, 463, 465, 477, 479. 
Perianth, 252. 
Periblem, 239, 240, 247. 
Pericentral cell, 59, 60. 
Pericycle, 241. 
Peridenn, 419. 
Peridineae, 54. 
Peridium, 90. 
Perigyny, 255. 
Perinium, 144, 147, 174, 175. 
Periplasm, 66. 
Perisperm, 270. 
Perithecium, 76, 77, 78. 
Peronospora, 67. 
Peronosporales, 65. 
Persistence, 457. 
Petal, 252. 
Petioles, sensitive, 472. 
Peziza, 72. 
Pezizales, 71. 
Phaeophyceae, 44. 
Phaeosporales, 45. 
Phallales, 91. 
Phanerogams, 180. 
Phaseolus, in darkness, 437; leaf movements, 
456. 
Phellogen, 240, 419. 
Phloem, 124, 345, 394. 
Phosphorus, source of, 379. 
Photeolic movements, 455, 456. 
Photosynthesis, 363 ; process, 375 ; prod- 
ucts, 373. 
Phototaxy, 449. 
Phototropism, 473- 
Phycocyanin, 4. 
Phycoerythrin, 55. 
Phycomycetes, 62 ; conclusions, 69. 
Phycophaein, 44. 
Phycoxanthin, 44. 
Phylloglossum, 131, 132. 
Phyllosiphonic, 159. 
Phylogeny, 295. 
Physcia, 78. 
Physiology, 295. 
Phytophthora, 66. 
Pileus, 87, 88, 89. 
Pilobolus, 68, 333. 
Pilularia, 176. 
Pinaceae, 219. 
Pine, archegonium, 223; embryo, 226; 
male gametophyte, 224; needle, 220; 
pollen, 22 /; pollen tube, 225; stem sec- 
tion, 219; strobili, 220, 221; wounded, 
395- 
Pistil, 253, 254, 260. 
Pitcher plants, 385, 386. 
Pith rays, 150. 
Pitted vessels, 241. 
Placenta, 260. 
Plagiotropic organs, 458, 466, 478. 
Plantaginales, 282. 
Plasmodium, 2. 
Plasmolysis, 309. 
Plasmopara, 66. 
Plectascales, 74. 
Plerome, 239, 240, 247. 
Pleurocarpae, 121. 
Pleurococcus, 20, 21. 
Plowrightia, 76. 
Plum pockets, 71. 
Poa, penetrated by fungus, 381. 
Podocarpineae, 212. 
Podocarpus, 212 ; microsporophylls, 214. 
Poisons, 484. 
Polarity, 440. 
Pollen, 109 ; chamber, 183, 198, 210; chemo- 
tropism of, 474; sac, 260; tube, 201, 211, 
216, 2/7, 225, 235, 268, 269. 
Pollination, 268. 
Pollinium, 259. 
Polyembryony, 275. 
Polyhedra, 23. 
Polymorphism, rusts, 83. 
Polypodiaceae, 156; antheridium, 167 ; 
sporangia, 162. 
Polyporaceae, 88. 
Polyporus, 88. 
Polysiphonia, 58, 59, 60. 
Polysiphonous, algae, 45. 
Poly stele, 157. 
Polystichum, sporangium, 352. 
Pore fungi, 88. 
Porella, 103, 104, 105. 
Porogamy, 269. 
Portulaca, photeolic movements, 455. 
Postelsia, habit, 48. 
Potamogeton, escape of gas bubbles, 377. 
Potato rot, 66. 
Presentation time, 434, 461. 
Pressure, atmospheric, 350 ; barometric, 
329 ; diffusion, 304 ; root, 349. 
Primary tubercle, Lycopodium, 127. 
Primulales, 281. 
Procarp, 56, 59, 60. 
Proembryo, cycads, 200, 201, 202 ; Ginkgo, 
