INDEX 



377 



Nitrogen, groups and amounts in soil, 

 51 

 production and connection with 



photosynthesis, 55-56 

 source in ammonia salts, 54-55 

 in nitrates, 54-55 

 Nitrogen-fixing bacteria, 57-58 

 Nitrogenous substances, changes in, 

 at germination of seed, 224- 

 228 

 Nodules of leguminous plants, 59-61 

 Nucleoproteins, 229 

 Nutation, 333-334 



Nutrient elements, as regulators of 

 vital processes, 68-69 

 requirements of special plants, 91- 



94 

 solutions, composition of, 8 

 substances, as affecting yield, 84-88 

 Nutrition, with carbon dioxide, proc- 

 ess of, 10-13 

 mineral, 76-80 

 minor elements in, 67 

 Nyctinastic movements, 336-341 



O 

 Olsen, on hydrogen ions in plant dis- 

 tribution, 95-96 

 Oparin, on respiration, 273 

 Optical properties of chlorophyll, 26- 



31 

 Organic, acids, 215-219 



substances, as plant food, 199-247 

 translocation of, 243-247 

 Osborn, on proteins, 224 

 Osmometer, Dutrochet's, 111 



Pfeffer's, 111 

 Osmosis, general laws of, 107-112 

 Osmotic pressure, in plants, 115-116 

 methods of determining, 113-115 

 properties of cell sap, 112-116 

 value, 115-116 

 Osterhout, on ion antagonism in 



nutrition, 75 

 Ostwald, on colloids, 104 

 Overton, on lecithin, 218 



on protoplasmic membrane, 117 

 Oxidase, 271-272 



Oxidation, physiological, 269-275 

 Oxidizing enzymes, 270-272 

 Oxydo-reductases, 272 

 Oxygen, determination, 11 

 liberation, 10-13 

 methods of gathering, 11 



Palladin, on enzymes, 215 



on etiolated plants, 303 



on fermentation, 263-264 



on lecithin, 218 



on respiration, 270-274 

 Papain, 224 

 Parasites, 238-242 



Parasitic plants, nutrition of, 236-243 

 Parthenocarpy, 355 

 Pasteur, on alcoholic fermentation, 

 259 



nutrition of microorganisms, 236 



on racemic compounds, 234 

 Pepsin, 225 

 Peptases (see Pepsin). 

 Perennial plants, 342-345 

 Periodicity in growth, 288-293 

 Permeability of plasma membrane, 



123-124 

 Perrin, on colloids, 103 

 Pettenkoffer tubes, 251, 252 

 Pfeffer, on osmosis, 110-111 



on plasma membrane 117 

 Pfeffer's osmometer, 111 

 Pfliiger, on proteins, 230 

 Phosphatides. 215-219 

 Phosphorus, cycle in nature, 71 



in nutrition, 69 71 

 Photochemical process, 28 

 Photonasty, 337-338 

 Photoperiodism, 345-350 

 Photosynthesis, 25-26 



chemistry of, 26-31 



light assimilation in, 33 

 Phototropic chamber, 317 

 Phototropism, 314-322 

 Phytin, 71 

 Phytol, 19 



Pigments, accompanying chlorophyll, 

 21-22 



