580 



INDEX 



N 



Nails, 521. 



Names, scientific, 133, 142. 



Narcotics, 539, 553. 



Nature-study, of frog, 24. 



Nautilus, 413. 



Nereis, 348. 



Nerve-endings, 510. 



Nerves, 511. 



Nervous activity, frog, 56, 57 ; 

 human, 509-519; worm, 352; 

 reflex, 510; voluntary, 511. See 

 also irritability. 



Nervous organs, 57, 509-519 ; hy- 

 giene, 535-537. 



Nettle-cells, 325. 



Neuroptera, 388. 



Nitrogen, cycle, 128 ; as excretion, 

 508 ; in foods, 499 ; in soils, 99. 



Nucleus, 40. 



Nutrients, 460. 



Nutrition, animals, 56 ; human, 

 492-502. 



Nuts, 218. 



O 



Octopus, 413. 



Organisms, 2. 



Organs, 27 ; of frog, 36 ; plant, 67. 



Orthoptera, 388. 



Osmosis, 89. 



Ovary, in flowers, 204. 



Overwork, 535. 



Oviparous development, 63. 



Ovipositor, 381. 



Ovum, see egg-cell. 



Ovules, 78, 197. 



Oxidation, 7, 51, 125, 304. 



Oxygen, in animals, 52, 125; in 

 blood, 505 ; in cells, 506 ; in germi- 

 nation, 155; in plants, 110, 119, 

 125; in photosynthesis, 112. 



Oxygen-supply, animal, 52, 55 ; cray- 

 fish, 366; human, 502-506; 

 Hydra, 327; plant, 110-125. 



Oyster, 357, 409. 



Palate, human, 465. 

 Palisade cells, 75. 



Pancreas, human, 470. 

 Paramecium, 300-307. 

 Parasites, barnacle, 375 ; insect, 390 ; 



malarial, 312; plant, 100, 259, 



267 ; protozoan, 312-315 ; worms, 



341-345. 



Parthenogenesis, 196, 386. 

 Pasteur, 269, 284. 

 Pasteurization, 284. 

 Pepsin, 477. 

 Perianth, 203. 

 Pericardium, 30, 487. 

 Perennial, 177. 

 Petal, 203. 

 Petri dish, 257. 

 Phanerogams, 233. 

 Pharynx, human, 468. 

 Photosynthesis, 102. 

 Phylum, 137. 

 Physics, definition of, 6. 

 Physiology, 22 ; animal, 44-57 ; 



human, 457-524; plant, 85-120. 



See also under descriptions of types 



of animals and plants in Parts II 



and III. 

 Pistil, 205. 

 Pith-rays, 170. 



Placenta, animal, 452 ; plant, 80. 

 Planaria, 341. 

 Plant, biology of, 66-121. 

 Plant-lice, 386. 

 Plants, group of, 144. 

 Pleura, 503. 

 Pleurisy, 503. 

 Pleurococcus, 237. 

 Plumule, 83. 

 Pod, 79-81. 

 Pollen-grain, 197, 216. 

 Pollination, 77, 78, 197, 200, 201, 



216, 390. 

 Polyp, 332. 

 Porifera, 320-324. 

 Posterior, 26. 

 Pregnancy, 450. 

 Propagation, from roots, 162 ; from 



stems, 180; of seed-plants, 225- 



227. See also reproduction. 

 Proteins, 104, 497-500, 530. 

 Prothallium, 235. 

 Protonema, 243. 



