568 



BOTANY OF THE LIVING PLANT 



Ophioglossaceae, mycorhiza in, 197. 



Ophrydeae, mycorhizic germination 

 of, 201 (Fig. 152). 



Ophrys, young tuber of, 201 (Fig. 

 152). 



Opium Poppy, 512. 



Orchidaceae, 492, 497. 



Orchids, epiphytic, 178 ; endotrophic 

 mycorhiza of, 197 ; necessary, 199 

 (Figs. 150, 151, 152, 153). 



Orchis, young tuber of, 201 (Fig. 

 152) ; meiomery in, 235 ; flower 

 of, 492, 497 (Figs. 401, 402). 



Organic material, formation of new, 

 4.98. 



Orobancheae, 188. 



Orobanche, parasitism of, 193 (Fig. 

 144). 



Orj^za (Rice), analysis of, 547 ; 

 origin of, 548. 



Oscillatoria, 457 (Fig. 390). 



Osmotic control, upset by shock, 131. 



Osmotic pressure, 89. 



Osmunda (Royal Fern), 327 ; apex 

 of, 334 (Fig. 274). 



Ovary, the part of the pistil contain- 

 ing an ovule or ovules, 252 (Fig. 

 199) ; superior, where the ovary is 

 borne by the elongated receptacle 

 above the other parts, 237 (Fig. 

 185) ; inferior, where it appears 

 sunk in the shortened receptacle, 

 and below the outer parts, 238 

 (Figs. 187, 188). 



Ovule, the megasporangium of flower- 

 ing plants, which ripens into the 

 seed : 222, 252 ; structure of, 258 

 (Figs. 206, 207) ; of Pine, 310 

 (Figs, 252, 253) ; megaspore re- 

 tained within, 486. 



Ovuliferous scale, of Coniferae, 307, 

 309 (Fig. 252). 



Ovum, or egg, the female gamete, 

 260 (Fig, 206), 262 (Fig. 209) ; 

 270 (Fig. 214) ; 271 (Fig. 215) ; 

 of Pine, 311 (Fig. 258) ; of Selagin- 

 ella, 321 (Fig. 265) ; of Fern, 344 

 (Fig. 285) ; of Moss, 361 (Fig. 

 304) ; of Riccia, 367 ; of Brown 

 Seaweeds, 379, 381 ; of Fucus, 

 - 385 (Fig. 325) ; of Oedogonium, 

 393 ; of Pythium, 409 (Fig. 344), 

 416; retention of in archegonium, 

 484. 



Oxygen, given off in photo-synthesis, 

 100 (Fig. 73) ; absorbed in respira- 

 tion, 113 (Fig. 82). 



Paleae, inner chaffy bracts of the 



Grasses, 500, 503 (Fig. 406), 504. 

 Palisade parenchyma, 6i (Fig. 44), 



62 (Fig. 45), 64 (Fig. 46), 66, 



67. 

 Palm, stem of, 56 ; mechanical 



construction in stem of, 150 ; 



subdivision of leaf of, 157. 

 Palm-type of structure of stem, 44 



(Fig. 31)- 

 Palmella-state, of Euglena, 374. 

 Panicle, an indefinite inflorescence 



in which each pedicel branches, 



bearing several flowers, 226 (Fig. 



174)- 



Papaver (Poppy), 511 (Fig. 418). 

 P. somniferum, 512. 



Papaveraceae, 511. 



Papilionaceae, 522. 



Pappus, feathery bristles representing 

 the calyx in the Compositae, 290 

 (Fig. 234), 535. 



Parallel-development, 160, in Algae, 

 401. 



Parallel venation of Monocotyledons, 

 61. 



Paraphyses of Mushroom, 453. 



Parasite, an organism that derives 

 organic supply from some other 

 living organism, 187 ; partial, 188 ; 

 complete, 190. 



Parasitic habit of Fungi, 402. 



Parasitism, as source of combined 

 nitrogen, 107. 



Paratonic movements, resulting from 

 external stimulus, 124. 



Parenchyma, cells roughly oblong in 

 form, and not much longer than 

 broad, 28 (Figs. 12, 14, 16), 50 

 (Fig. 37)- 



Parietal cells, which form inner wall 

 of pollen-sac, 248 (Fig. 195). 



Paris, mycorhiza in, 197, 494. 



Parmelia, 438 (Fig. 372). 



Parsnip, origin and analysis of, 541. 



Parthenogenesis, somatic, 477 ; gene- 

 rative, 478. 



Partial parasites, those which are 

 only partly dependent on parasit- 

 ism for nutrition ; they are usually 

 green, 188. 



Pastinaca sativa (Parsnip), 541. 



Pathogenic organisms, varying viru- 

 lence of, 204. 



Pea (Pisum sativum), 523 ; analysis 

 of, 542 ; origin of, 543 ; root-tip of, 

 77 (Fig. 61, B) ; tendril, 182. 



