714 - Index 



510 n.; frequencies, 512-13; nature of, basic, 



526-29; point, 510 n. 

 Mycelium. 173, 175, 604, 608 

 Myelin, 288 

 Myofibrils, 28, 30, 286 

 Myxomycophytes (slime molds), 602-04 

 Myonemes, 195, 196 

 Myosin, 436, 439 

 Myxamoebae, 603 

 Myxedema, 404 



N 



Nachmansohn, D., 193 



Nannochloris, 589 



Nasal passages, 297, 298 



Natural habitat, 573 



Natural selection, 429. 541-43; genetics and, 

 548-49 



Nautiluses, 649, 652, 653 



Neanderthal man, 571 



Nectar glands, 224 



Nemathelminthes (nematodes), 644—47 



Nemertinea, 641, 642 



Nephric filtrate, nature of, 373-74; plasma and 

 urine compared to, 374 



Nephridia, 371 



Nephritis, 376 



Nephrons. 372-73 



Nephrostome, 371 



Nerve cells (see Neurons) 



Nerve cord, origin of, 281-82 



Nerve endings, 453 



Nerve impulses, 447-48 



Nerve net of Hydra, 449-50 



Nerve tissues, 287-88 



Nerves, 288: autonomic, 465-67; cranial, 461, 

 462; craniospinal, 460; excitability in fibers of, 

 448-49; parasympathetic, 465-67; spinal. 460- 

 61; sympathetic, 305, 465-67; vagus, 305 



Nervous system, 447-70; autonomic, 305, 465. 

 466, 467: behavior, 467-70; central (see Central 

 nervous system); central vs. peripheral parts of. 

 451-52; of earthworm, 451-53; excitability in 

 nerve fibers, 448-49; man and other vertebrates, 

 458-67; nerve cell bodies and dendrites, func- 

 tions of, 455-58; nerve impulses, 447-48; nerve 

 net of Hydra. 449-50; neurons of vertebrates, 

 453-55; parasympathetic, 466, 467; sympathetic, 

 407; visceral reflexes, 465-67 



Neural tube, 281 



Neurofibrils, 30 



Neurons, 19, 21. 287, 288; association. 452, 459, 

 460, 462; motor, 462; pacemaker, 456; postgan- 

 glionic, 466; preganglionic, 466; sensory, 461. 

 462; of vertebrates, 453-55 



Neurosecretion, 414, 454-55 



Neurospom, 354, 529 



Neutral parasites, 179-80 



Neutral red dye. 29 



Neutral solutions, 73-74 



Neutrons, 70 n. 



Niacin, 104, 146, 348, 352 



Night blindness, 348, 350 



Nitella, 168, 198,237-38 



Nitrite bacteria, 182, 185 



NHrobacter, 182 



Nitrogen, 65, 75; free, 177; inorganic, return to 

 soil and air, 177 



Nitrogen cycle, 183-85 



Nitrogen-fixing bacteria, 180-81, 185 



Nitrogenous waste, 138 



Nitrosomonas, 182 



Nodes, 237; lymph, 334-35 



Nonelectrolytes, 73 



Nonessential amino acids, 136 



Noradrenalin, 414 



Notochord, 281, 664; origin of, 281-82 



Nuclear membrane, 16, 3f 



Nucleic acids, 10 n„ 88, 90, 137 



Nucleoli, 7, 22. 23, 41 



Nucleoplasm, 74 



Nucleoproteins. 10, 88-89 



Nucleotides, 88, 89 



Nucleus, 7, 16, 17, 18, 22-23. 598; responsibilities 

 of, functional, 34—35; zvgote. 57 



Nurenberg, M. W„ 136 



Nutrition. 4-5, 126; absorption, 128. 130-31; 

 algae, multicellular, 236-38; animal cells, 126- 

 39; autotrophic, 182; in bread mold, 175-76; 

 brvophytes, 239-42; chemotrophic, 181-82; 

 conservation of food elements, 173-87; diges- 

 tion, 128. 129-30; distribution, 128, 131-32; 

 egestion, 128, 131; embryo, 388-93; excretion. 

 128, 133; excretion in plants, 256; green plant 

 cells. 158-71; heterotrophic, 182; holophytic 

 (see Holophytic nutrition); holozoic (see Holo- 

 zoic nutrition); ingestion, 128-29; liverworts, 

 239-40; metabolism. 128. 132, 133-39; mixo- 

 trophic, 178, 182; modes of, 126-28, 182; mosses, 

 240-41; organic substances in plants, distribu- 

 tion of. 253; parasitic, 178-81, 182; plants, 

 multicellular, 236-57; respiration, 128, 132-33; 

 respiration in plants, 255-56; saprophytic, 174— 

 78, 182; sporophyte generation, ascendance of. 

 242; storage problem in plants, 257; of sulfur 

 bacteria, 181; vascular plants, organs and tissues 

 of, 242-53; of yeasts, 174-75 



O 



Obelia, 395, 632-33 



Observation, in scientific method, 12-13 



Ochoa, S., 161, 526 



