INDEX 



443 



Pilea, 253 ; movements of stamens of, 

 147. 



Pilobolus, autotropism of, 189; P. crystal- 

 linus, dispersal of, 150, 153; helio- 

 tropism of, 173, 175. 



Pilogyne suains, growth of curving tendril 

 of, 57, Fig. 18. 



Pinguicula, 85 ; absence of granulation in, 

 90 ; irritability of, 84 ; P. vulgaris, 

 irritability of, 87. 



Pinus, orientation of branches of, 254, 255. 



Pisum, 182, 335, 418 ; curvature of epicotyl 

 of, 27 ; electrical currents in, 390 ; 

 tendrils of, 42, 43 ; P. sativum, 

 changes of tone in, 207 ; curvature of 

 etiolated seedlings of, 23 ; thermo- 

 tropism of, 177. 



Pith, geotropism of, 243 ; influence of, on 

 curvature, 243. 



Plagiotropic shoots, orientation of leaves 

 on, 259, 260. 



Plagiotropism, definition of, 155 ; origin of, 

 I 58> 159? 160 ; in Hedera, 252; in 

 leaves, 255, 256 ; in Marchantia, 251 ; 

 in rhizomes, 249 ; in runners, 250 ; in 

 trees, 253. 



Planch on, 117. 



Plantago media, influence of light on 

 leaves of, 105. 



Plasmodia, influence of changes of tempera- 

 ture on, 317. 



Plasmodiophora, 276. 



Plasmolysis, influence of, on curvature, 246, 

 247 ; on irritability, 74, 201 ; on 

 streaming, 355 ; stimulatory, 75. 



Plaster-of-paris cleistogamy, ico. 



Plenge, 265, 269. 



Pleospora scirpicola, 150, Fig. 34. 



Pleurotaenium, phototaxis of, 325. 



Pliny, in. 



Plowmann, 394. 



Pneumatophores, 164. 



Poggioli, 176. 



Poikilotherms, 366, 367. 



Poisons, influence of, on streaming, 342. 



Polarity, influence of centrifugal forces on, 

 336- 



Polarized light, heliotropic action of, 170. 



Pollen-tubes, aerotropism of, 182 ; chemo- 

 tropism of, 180, 181 ; discriminatory 

 power of, 214 ; indifference of, to con- 

 tact, 83 ; penetration of, 181, 182, 190. 



Pollock, 200, 234, 243 ; on traumatropism, 

 185. 



Polygonaceae, geotropism of nodes of, 

 242. 



Polygonatum multiflorum, 253. 



Polygonum, influence of etiolation on nuta- 

 tion of, 30 ; P. aviculare, geotropism 

 of, 165 ; orientation of, 250 ; twining 

 of, 33 ; P. complexum, 38 ; P. convol- 

 vulus, twining of, 38, 40 ; influence of 

 light on circumnutation of, 42 ; P. 



Fagopyrum, influence of etiolation on 



nutation of, 28 ; on twining of, 35. 

 Polyphagus euglenae, 324 ; locomotion of, 



265. 



Polypodiaceae, dehiscence of, 152. 

 Polyporus squamosus, influence of light on 



formation of pileus of, 416. 

 Polytoma uvella, chemotaxis of, 351; gal- 



vanotaxis of, 361 ; geotaxis of, 337. 

 Popoff, 377. 



PopOW, 102. 



Poppy, changes of tone in, 205 ; geotropism 

 of peduncle of, 164. 



Porliera, 13 ; sleep-movements of, 102 ; P. 

 hygrometrica, hydronastic movements 

 of, 118 ; reaction of operated pulvinus 

 of, 138. 



Portheim, 417. 



Portulaca, sleep-movements of, 102 ; P. 

 sativa, photonastic pulvini of, 109. 



Portulaceae, motile stamens in, 82. 



Posternak, 282. 



Potassium salts, chemotactic and tropic 

 action of, 181, 349; repellent action of, 

 351) 35 2 3535 suppression of irrita- 

 bility by, 86. 



Potatoes, production of heat by, 375, 376. 



Potentilla reptans, orientation of, 250. 



Potts, 183, 304. 



Prantl,3l, 174, 175. 



Precipitation, influence of light on, 229. 



Precipitation membranes, influence of sur- 

 face-tension on, 281. 



Presentation period, 209, 211, 417. 



Pressure, influence of, on pulsating vacuoles,, 

 297. 



Preuss, on tropism of old leaves, 231. 



Prillieux, 327. 



Primula elatior, influence of light on, 105. 



Pringsheim, 149, 288, 320, 327, 333, 342. 



Prinz, 380. 



Prisms, use of, 228. 



Prothallus, orientation of, 252. 



Protoplasm, accumulation of, during curva- 

 ture, 219; on injury, 359; on stimu- 

 lation, 1 1 ; consistency of, 276, 277 ; 

 changes in, 279 ; deformation of, by 

 changes of temperature, &c., 308, 316, 

 317 ; due to light, 320 ; extracellular, 

 272, 273 ; influence of cohesion of, on 

 movement, 16 ; of light, 229. 



Protoplasmic connexions, action of, 269; 

 resistance to flow in, 288 ; use of, for 

 transference of stimuli, 93 ; for trans- 

 location, 91. 



Protoplasmic fibrillae, function of, 201. 



Protoplasmic streaming, 283; diagram of, 

 291, Fig. 51 ; duration of, 283-4 ; excita- 

 tion of, 284; history of, 289 ; importance 

 of, 285 ; influence of alkaloids and 

 poisons on, 342, of acid and alkalies, 

 343, of oxygen, 340, 341, of shape of 

 cell on, 292 ; of, on pulsating vacuoles, 



