INDEX 



489 



Plankton, 234. 



Plant breeding, principles of, 464- 

 478. 



Plant kingdom, 207. 



Plant migration, 431; by seeds, 432; 

 by fruits, 432; by layering, 433; 

 fertility of species, 434; by physi- 

 cal and chemical conditions of soil, 

 4355 by climatic changes, 435. 



Plant societies, 439-454. 



Plasmopora viticola, 256. 



Platycerium alcicorne, 338, 339. 



Pleurococcus vulgaris, 220, 229, 273, 

 274. 



Plowrightia morbosa, 265, 267. 



Plum family, 407. 



Plum, fruit, 192, 408. 



Plum rot, 267. 



Plums, 408. 



Plumule, 2, 7, 8. 



Pod, 152, 191, 409. 



Pogonatum, 321. 



Poison ivy, 29. 



Poisonous mushrooms, 291, 295, 296. 



Pollen, 147, 148, 167-184. 



Pollen grain, 182-184, 360, 365, 368- 

 370, 379> 380. 



Pollen tube, 182-184, 365, 370, 379. 



Pollination, 167-184. 



Pollination, artificial, 468. 



Pollination, close, 169-171; cross, 

 169, 171-184. 



Pollinium, 168, 177. 



Polymorphism, 247. 



Polypodiaceae, 330. 



Polypodium vulgare, 329. 



Polypody fern, 330; fruit of, 329. 



Polyporaceae, 296. 



Polyporus applanatus, 298. 



Polyporus borealis, 131. 



Polyporus igniarius, 298. 



Polyporus mollis, 132. 



Polyporus pinicola, 297. 



Polysiphonia, 241, 242, 324. 



Polystichum acrostichoides, 330. 



Polytrichum, 317. 



Pomaceae, 406. 



Pome fruit, 195, 407. 



Pomelo, 412. 



Populus dilitata, 48. 



Pore fungi, 292, 296-298. 



Postelsia, 236. 



Potassium, 117, 118. 



Potato, 44, 416. 



Potato family, 416. 



Powdery mildews, 262-265. 



Prairie societies, 446. 



Prickly ash, 411. 



Prickly lettuce, 78, 200, 201. 



Primrose, evening, 145-148; La- 

 mark's, 461; dwarf, 462. 



Privet, 416. 



Procarp, 240. 



Promycelium, 275, 277, 279, 284, 

 285. 



Pronuba, pollination by, 171. 



Prop roots, 29. 



Protease, 135. 



Proteid grains, 14, 15. 



Proteids, 19. 



Prothallium of angiosperms, 380. 



Prothallium (female gamete plant) 

 of Cycas, 368. 



Prothallium of ferns, 329, 334, 



335- 



Prothallium of Selaginella, 348, 349. 

 Prothallus, 329. 

 Protococcoidese, 209, 220, 230. 

 Protococcus vulgaris, 220. 

 Protonema, 316, 320, 321, 325, 334, 



34. 



Protoplasm, 13, 33-35, 182, 213-217. 

 Prunes, 408. 



Prunus amygdalinus, 408. 

 Prunus persica, 407. 

 Prunus serotina, 409. 

 Pseudomonas radicicola, 121. 

 Pteridium aquilinum, 330. 

 Pteridophyta, 207, 210. 

 Pteridophytes, 207. 

 Pteris aquilina, 330; germinating 



spores, 334. 

 Pteris cretica, 340. 

 Pteris serrulata, embryo of, 337, 



339- 



Pteris serrulata, spore of, 334. 

 Ptomaines, 133. 

 Ptyalin, 134. 

 Puccinia graminis, 280. 

 Puccinia malvacearum, 290. 

 Puccinia podophylli, 290. 

 Puccinia rubigo-vera, 287. 

 Puccinia taraxaci, 290. 

 Puffballs, 292, 299. 

 Pumpkin seed, 7. 

 Putrefaction, 133. 

 Pyrenoid, 213, 214. 

 Pyxidium, 192, 



