INDEX AND GLOSSARY 



689 



Pleiomery, in the flower, where the 

 number of parts of one category is 

 greater than the fundamental num- 

 ber for that flower, 266. 



Pleurocarpic, of Mosses which fruit 

 laterally, 467. 



Pleurocladia, zoospores of, 381 (Fig. 

 284). 



Pleurococcus, 2 (Fig. 1) ; 361, 364 

 (Fig. 269) ; 365 (see Protococcus). 



Plum, analysis of, 657. 



Plumule, the apical leafy bud of the 

 embfyo, 7. 



Plurilocular sporangia, 382 (Fig. 286). 



Pneumacoccus, 453. 



Poa alpina, viviparous habit of, 248. 



Podosphaera clandestina (Hawthorn 

 Mildew), 420. 



Poisons, 31. 



Polar nuclei, fusion of in Monotropa, 

 298 (Fig. 219). 



Pollen-grains, of Flowering Plants, 

 283 (Fig. 204) ; development of, 

 285 (Figs. 206, 207) ; germination 

 of, 3°3, 3°4 ; of pine . 534 (Fig. 

 421), 535 (Fig. 423)- 



Pollen-mother-cells, those cells which 

 after tetrad-division, give rise to 

 pollen, 285 (Figs. 206, 207). 



Pollen-sac, the microsporangium of 

 Flowering Plants, containing the 

 microspores, or pollen-grains, 222, 

 282 (Fig. 203), 352 ; development 

 of, 284 (Figs. 205, 206). 



Pollen-tetrad, a group of four cells, 

 resulting from the tetrad-division 

 of a pollen-mother-cell, 283 (Fig. 

 204), 564 (Fig. 430). 



Pollen-tube, formation of, 283 ; cul- 

 ture solutions for, 303 ; negative 

 aerotropism of, 160, 161 (Fig, 97, 

 A) ; influences upon growth of, 161, 

 304 (Figs. 222, 223) ; of Pine, 535 

 (Fig. 423, 424) ; of Zamia, 527 

 (Fig. 415). 



Pollination, the transfer of pollen- 

 grains from the pollen-sac to the 

 stigma, Chap. xvii. 



Pollinia of Orchis, 612 (Fig. 460). 



Polycarpicae, 622. 



Polygonum viviparum, bulbils in 

 place of flowers, 247. 



Polyploid, an individual possessing in 

 its somatic cells more than the 

 normal (diploid) number of chromo- 

 some sets, 581-584 (Figs. 443, 444) ; 

 polyploid series, 584. 



Polypodium, dorsiventrality of, 208 

 (Fig. 140) ; archegonia of, 502 

 (Fig. 394) ; sporeling of, 592, 597. 



Polyporus, 393. -H 2 - 



Polysaccharides, 123. 



Polysiphonia, alternation in, 390, 393, 



546. 

 Polystichum, apospory in, 507 (Hg. 



401). 

 Polytrichum, conducting tissue of, 



464 (Fig. 358) ; leaf structure of, 



465 (Fig. 359) ; perichaetia of, 467. 

 Poplar, adventitious buds on root, 



247 (Fig. 171). 



Poppy, geotropic changes in, 154. 



Poppy (Papaver), pore capsule of, 

 325 (Fig. 244), 625 (Fig. 476). 



Populus alba, adventitious buds on 

 root, 247 (Fig. 171) ; tremula, 

 lamina of, 72 (Fig. 47). 



Porogamy, where in Seed-Plants 

 fertilisation is through the micro- 

 pyle, 3°5 (Fig. 226). 



Porotrichum, aquatic habit of, 462. 



Posterior, side of a flower next the 

 axis, 263. 



Potassium, absorption from soil, no. 



Potato, cortex of, 42 (Fig. 22) ; cor- 

 rection in, 218 (Fig. 147) ; leuco- 

 plasts of, 124 (Fig, 81) ; starch- 

 grains, 125 (Fig. 82) ; early forma- 

 tion of tubers in, 244 (Fig. 168) ; 

 vegetative propagation of, 218 

 (Figs. 147, 168) ; tissue attacked 

 by Pythium, 401 (Fig. 301) ; flower 

 of, 642 (Fig. 493) ; origin of, 653 ; 

 analysis of, 655. 



Potato Disease (Phytophthora in- 

 festans) 396, 406 (Figs. 3 5"309). 



Potentilla, floral construction of, 267 

 (Fig. 191), 633 (Fig. 484). 



Potometer, an instrument for measur- 

 ing the absorption of water, 101 

 (Fig. 69). 



Presentation time, 155, 160 ; sur- 

 faces, 601. 



Primary phloem, bast formed without 

 cambial activity, 58 (Fig. 37). 



Primary xylem, wood formed with- 

 out cambial activity, 58 (Fig. 37). 



Primordial cell, a naked protoplast, 

 169 (Fig. 104). 



Primrose (Primula vulgaris), 640 

 (Fig. 492). 



Primula Kewensis, an allo-polyploid, 



583. 

 Primulaceae. meristic differences in, 



265, 640 (Fig. 492). 

 Primulales, 640. 

 Principle of Maximum Exposure, 



603. 

 Principle of Similarity, 591. 

 Productivity, by seeds, 332. 



