INDEX 



443 



Pollen tube of, Angiosperms, 363, 

 364 (fig.), 365, 367 (fig.) ; 

 Conifers, 349 (fig.), 350, 351 

 (fig-). 353 ; Cycads, 325 (fig.), 

 326, 327 (fig-), 332. 



Pollination, by insects, 46, 361, 

 373 I by water, 361 ; by wind, 

 361, 373 ; of Angiosperms, 

 355, 356, 363, 372 ; of Conifers, 

 345, 348, 349, 35 ; of Cycads, 

 326 ; of Lyginopteris, 330, 331. 



Pollination-drop, 332 ; of Conifers, 

 348 ; of Cycads, 326. 



Pollinia (of Orchids), 361, 362 (fig.). 



Polyarch roots, 69, 70 (fig.). 



Polyembryony, 371 (fig.), 372, 390. 



Polygonaceae, 356. 



Polygonum, ovule of, 358 (fig.). 



Polygonum convolvulus, extrafloral 

 nectaries of, 148 ; petiole of, 



ii3 (fig-)- 



Polypetalous Dicotyledons, 357. 

 Polypody (Poly podium), 309 ; sori 



of, 291 (fig.), 295. 

 Polyporus, 255 ; P. squamosus, 250 



(fig-)- 

 Polysaccharides, 31, 43, 44, 48, 



231 ; hydrolysis of, 46, 48. 

 Polystictis versicolor, Plate II. 

 Polytrichum, 274 (fig.), 276, 286; 



P. juniperinum, 269. 

 Pond-scums (Algae), 195 et seq. 

 Pond weed(Potamogeton) , stamen of, 



359 (fig.) ; stem-structure of, 



172, 174 (fig.). 

 Pondweed - family (Potamogeton- 



aceae), 178. 

 Poplar (Populus), 130, 141, 142 ; 



vessels of, 28, 35 (fig.). 

 Poppy (Papaver), 61, 155, 359. 

 Poppy-family (Papaveraceae), 153, 



154; 



Populations, inheritance among, 



378. 

 Populus, 130, 141, 142 ; vessels of, 



28, 35 (fig-)- 

 Pores of, Liverworts, 273 (fig.) ; 



pollen-grains of Angiosperms, 



362 (fig.) ; sieve-plates, 28 ; 



stomata, 96, 98, 99 (fig.), 100. 

 Porogamy, 364 (fig.), 365. 

 Porometer, 99, 100. 

 Potamogeton, 359 (fig.) ; P. lucens, 



172 ; P. natans, 172, 174 (fig.) ; 



P. pectinatus, 172. 

 Potamogetonaceae, 178. 

 Potash, and callose, 82 ; and cork, 



136 ; and fats, 49. 



Potato (Solanum tuberosum), food- 

 content of, 41, 42 (fig.), 43, 50, 

 52, 53 ; starch of, 41, 42 (fig.). 



Potato-blight (Phytophthora in- 

 festans), 230, 231, 253, 254 ; 

 structure and reproduction of, 

 234, 235 (fig-), 236. 



Potato-family (Solanaceae), 58, 60, 

 61, 81. 



Preservation of 'fossil-plants, 312, 

 328 ; of plant-material, 404. 



Prickles, 104. 



Prickly Pear, 392. 



Prickly Saltwort (Salsola kali], leaf 

 of, 94, 1 66. 



Primary endosperm nucleus (of 

 Angiosperms), 366 (fig.). 



Primary medullary rays, 76, 78 

 (fig.), 118; of Conifers, 340; 

 of secondarily thickened stems, 

 119 (fig.), 1 20, 122, 124; of 

 secondarily thickened roots, 

 132. 



Primrose (Primula), hairs of, 105 

 (fig.) ; hybrids of, 387, 388 



(fig-)- 



Primulaceae, 356. 



Procambial strands, 89, 90, 117, 

 171. 



Proembryo of, Angiosperms, 368, 

 369 (fig.), 371 (fig.), 372; 

 Conifers, 350, 351 (fig.) ; 

 Cycads, 327 (fig.). 



Prop-roots, structure of , 73, 74 (fig.). 



Prosenchymatous cells, 27, 32, 37. 



Proteaceae, distribution of, 394 (fig.)- 



Proteases, 53. 



Protection against, animals, 39, 48, 

 58, 64, 104, 106, 126, 157 ; 

 excessive transpiration, 64, 91, 

 92, 106, 137, 158-65, 203 ; 

 heat-rays, 64, 95, 102, 138 ; 

 injury, 92, 115, 142, 155; 

 intense light, 95, 102, no, in, 

 112, 199; parasites, 138, 142. 



Protection of embryos, 321, 332, 

 333, 373 ; of lateral roots, 72. 



Protective tissues, 91 et seq., 135 

 et seq. 



Proteins, 2, 7, 14, 40, 50-52, 53, 

 143, 262, 343 ; decomposition 

 of, by Bacteria, 265 ; hydroly- 

 sis of, 52 ; in latex, 155 ; re- 

 actions of, 3, 49 ; soluble, 50 ; 

 translocation of, 52, 88. 



Proteolytic enzymes, 52, 53, 54, 

 149. 



Prothallus of, Angiosperms, 373 ; 



