INDEX 



379 



Netted venation, 63, 65 



Nicotiana, flower of, 190 



Nitrate bacteria, 32, 33 



Nitrification, 32 



Nitrite bacteria, 32, 33 



Nitrohacter, 32 



Nitrogen cycle, 32, 33 



Nitrogen, importance of, 31, 168 



Nitrogen-fixing bacteria, 32, 33, 175 



Nitromonas, 32 



Node, 90, 92 



Nomenclature, 260 



Nostoc, 266 



Nucellus, 197, 345, 346, 358 



Nucleus, 45, 139 



Nut, 200 



Nutrient materials, 118 



Nym-phaea, pollen of, 186 



Oak, stem of, 105, 107 



wood of, 110 

 Objections to theory of Natural 



Selection, 237 

 Oedogonium, 245, 270, 271 

 Olein, 121 



One-celled green algae, 267 

 Oogonium, 271 

 Oospore, 269 

 Operculum, 319, 321 

 Ophioglossales, 333 

 Opposite leaf arrangement, 91 

 Optimum, as of temperature, etc., 



157 

 Orchidales, 366 

 Organ, 17, 246 

 Organic cycle, 118, 119 



matter in soil, 30 

 Organisms, in soil, 31 

 Organization, 246 

 "Origin of Species," 7, 235 

 Orthogenesis, 238 

 Oscillatoria, 266 

 Osmosis, 19, 47-55 



in growing regions, 55 



in the plant cell, 51-53 



Osmotic movement, of dissolved 

 substances, 48 



of solvents, 49 



rate of, 52 

 Osmotic pull in sap ascent, 111 

 Ovary, 185, 355 



Overproduction of offspring, 236 

 Ovulate cone, 353 

 Ovule, 185, 255, 345, 346 



evolution of, 255 

 Oxidase, 129 



Oxidation, in respiration, 126 

 Oxygen, absorbed in respiration, 

 126, 129 



b3'-product of photosynthesis, 73 



Palaeobotany, 3 



Palisade cell, of leaf, 67, 68 



layer of leaf, 66, 67 

 Palmales, 365 

 Palmitin, 121 

 Panicle, 193 

 Papilionaceous, 363 

 Pappus, 364 

 Parallel venation, 63, 65 

 Paraphyses, 293 

 Parasite, 171, 172, 284 

 Parenchyma, 96 

 Parmelia, 304 

 Pasteur, 286, 287 

 Pea, germination of, 202 



inheritance in, 213 

 Pediastrum, 269, 270 

 Penicillium, 296 

 Pepsin, 124 

 Percolating water, 25 

 Perianth, 187 

 Pericarp, 196, 199 

 Peridium, 302 

 Perithecium, 294 

 Perisporiales, 295 



Permeability of membranes, 49, 50 

 Peronosporales, 291 

 Petal, 185, 187 

 Petiole, of leaf. 63, (;4 

 Peziza, 293, 294 



