440 



INDEX 



Opium Poppy (Papaver somniferum), 



61, 155. 



Optical section, 6 (fig.), 401. 

 Orange (Citrus aurantium), 62, 151 ; 



polyembryony of, 371 (fig.), 



372, 390. 

 Orchids (Orchidacecs) , 355 ; aerial 



roots of, 73-5 (fig.) ; pollen of, 



361. 



Orchis morio, pollen of, 362 (fig.). 

 Oregon Pine (Pseudotsugadouglasii), 



129. 



Organic acids, 60. 

 Organic material, absorption of, by 



Fungi, 230, 232, 236, 237, 259 ; 



by insectivorous plants, 149, 



I 5', by mycorrhiza, 72, 252; 



by parasitic Angiosperms, 179. 

 Origin of new species, 378, 380, 381, 



382, 393- 



Orthotropous ovules, 358 (fig.). 

 Oryza saliva,^, 53, 257 ; starch of, 



42 (fig.), 43. 

 Osazones, 47 (fig.). 

 Oscillator ia, 205. 

 Osmic acid, and fats, 49. 

 Osmometers, 402, 403. 

 Osmosis, 8. 



Osmotic pressure, 8, 10 ; deter- 

 mination of, 10, n, 12, 15 ; of 



different strengths of sea-water, 



402, 403 ; of guard-cells, 100 ; 



of food-reserves, n, 44, 45 ; 



role of, in growth of plant-cells, 



26. 

 Osmunda regalis, habit of, 289, 309 



(fig.) ; prothallus of, 304 ; 



sporangia of, 300, 309 (fig.). 

 Osterhout, 13, 402. 

 Ovary (of Angiosperms), 334, 354-6, 



364, 365- 



Ovules of, Angiosperms, 354, 356, 

 357-9 (figs.), 365, 366 (fig.) ; 

 Conifers, 334, 336, 347 (fig.), 

 348, 349 (fig.) ; Cycads, 324, 

 325 (fig.) ; Lyginopteris, 328, 

 33. 33 1 > parasites, 179, 

 365- 



Ovuliferous scale (of Conifers), 347 

 (fig.), 348, 352 (fig.), 353- 



Ovum. See Egg. 



Oxalate of lime, 58, 59, 130, 237 ; 

 reactions of, 59. 



Oxalic acid, 58. 



Oxidases (oxidising enzymes), 55, 



155. 



Oxygen and Bacteria, 263 ; and 

 protoplasmic movement, 4. 



Paeony (Pesonia], 8. 



Palaeozoic period, plants of, 311. 



Palisade tissue, 38 (fig.), 107, 108 

 (fig.), 109, 110, 161 (fig.); arm 

 , no, in ; function of, 107, 

 109 ; of Alpines, 170 ; of 

 centric leaves, 11 6, 166 ; of 

 stems, 167 ; of sun- and shade- 

 leaves, 169 (fig.) ; of Taxus- 

 leaf, 342 (fig.). 



Palmella-stage of, Chlamydomonas, 

 182 (fig.), 184; Ulothrix, 214, 



215 (fig-)- 

 Palmitic acid, 49. 

 Palms, 44, 117. 



Papaver somnifenim, 61, 155. 

 Papaveraceae, 153, 154. 

 Paper, 35, 129. 

 Papillae, 103, 148, 342 (fig.) ; stig- 



matic, 356, 364. 

 Para-rubber (Hevea brasiliensis), 



156, 157- 



Parallel venation, 112. 



Parasites, protection against, 138, 

 142. 



Parasitic Angiosperms, 178 (fig.), 

 179, 231, 365, 372 ; Bacteria, 

 263; Fungi, -230 et seq., 252-5. 



Parasitism, 231, 247, 248, 252, 259, 

 264, 281, 288, 372 ; and im- 

 munity, 253. 



Parenchyma, 27, 33, 69. 



Parenchyma-sheath, 112, 113. 



Parenchymatous cells, 27, 32, 65, 

 76. 



Parietal placentation, 356. 



Parmelia physodes, 258 (fig.). 



Passage-cells of, endodermis, 70 

 (fig.), 71, 75 (fig.) ; exodermis, 

 67, 74, 75 (fig.). 



Passive hydathodes, 148. 



Pathogenic Bacteria, 263, 264. 



Pea (Pisum), 356, 370 ; hybrids of, 

 383, 384, 386 ; mutation in, 

 381 (fig.) ; protein of, 50, 52 ; 

 root of, 72, 74 ; starch of, 42 



(fig.)- 



Pea-mildew (Erysiphepolygom), 243. 

 Pea-nut (Arachis hypogcea], 49, 53. 

 Pear (Pyrus), 60 ; stone-cells of, 



30 (figs.), 32, 33. 

 Pectic substances, 31. 

 Pectose, 231. 



Pediastrum, 191 (fig.), 192. 

 Pelargonium, hairs of, 105. 

 Pellia, 407 ; anatomy of, 272, 278 



(fig.) ; antheridia of, 277, 278 



(fig.) ; archegonia of, 280, 381 



