INDEX 
635 
Pollen-grain, 401, 436 
Pollen-sacs, 436 
Pollination, 401, 427 
Pollinium, 477, 501 
Polypetalae, 456 
Polypodium, 154, 156, 159 
irioides, 154 
punctatum, 153 
Polytrichum commune, 206 
Populus, 457 
Porella navicularis, 211, 212 
Potato, 335, 347, 480 
blight, 313 
rot, 292 
tuber, 8 1 
Potatoes, little, 291 
Potonie, 598 
Pressure, osmotic, 58 
and growth, osmotic, 113 
Priestley, Joseph, 73, 74 
Primofilices, 616 
Proangiosperms, 606 
Propagation, 180 
Prophylaxis, 310 
Protease, 79, 86 
Protein, 16 
Proteins, 71 
manufacture of, 84 
Prothallus, 166, 167 
Protonema, 163, 166 
Protoplasm, 14, 15 
properties of, 19 
Protoplast, 1 6 
Pseudoborniales, 618 
Pseudomonas radicicola, 82, 83, 
3i8, 332 
Pseudopodium, 200, 201 
Psilotales, 618 
Pteridophytes, 366, 388 
Pteridosperms, 592 
significance of, 598 
Pteris, 156 
Pteris aquilina, 149, 155 
longifolia, 153 
Pteropsida, 616 
Ptyalin, 100 
Puccinia graminis, 299 
Punk, 303 
Purity of gametes, theory of, 555 
Pussy-willow, 458 
Putrefaction, 319 
Pyrenoids, 353 
Pyrolaceae, 473 
Pythium de Baryanum, 291 
Quarantine, 311 
Quercus, 336 
novimericana, 34 
Qu6telet, 524 
Qugtelet's curve, 525, 526 
Radicle, 381, 464 
Ranunculaceae, 459 
Ranunculus, 459, 460, 461, 462 
aquatilis, 507 
Rattan, 495 
Rattlesnake fern, 176 
Ray, John, 453 
Recptacle, 155 
Redi, 89 
Reduction, 183, 184 
division, 185, 187 
Regeneration, 205 
Reproduction, asexual, 179 
by spores, 180 
cell-division and, 344 
essence of all, 180 
inheritance and, 544 
sexual, 179, 1 80 
