INDEX 



469 



Nostrils, 149, 152, 153 

 Notochord, 137, 142, 146 

 Nucleolus, 26 

 Nucleus, 9, 26, 27, 28, 77; during 



conjugation, 245; during endo- 



mixis, 248 



Nurture versus nature, 296-299 

 Nutrition of animals, 154-160 

 Nutritional chain, 330 



O 



Obelia, 414; life history, 218 



Oedogonium, 97, 98 



Oesophagus, 123, 131, 148-155 



Oil, 14; gland, 151 



Olfactory, bud, 196; lobe, 14&, 

 187, 189, 190; pouches, 196; 

 sense, 196 



Oligocene period, 358 



Onion leaf, 72 



Onoclea, 74 



Ontogeny, 364 (see Embryology) 



Oocytes, primary and secondary, 

 231 



Oogenesis, 231-233 



Oogonium, 224, 232 



Operculum, 141 



Opsonin, 338 



Optic capsule, 141, 145; cup, 199; 

 lobes, 188, 189} nerve, 152, 

 190; stalk, 199 



Order, in classification, 349 



Organ, 59; organ-forming sub- 

 stances, 256, 259 



Organic evolution, 262 (see Evolu- 

 tion) 



Organisms, adaptation of, 307- 

 344; colonial, 55, 56; micro- 

 cosm, 20; structure of multi- 

 cellular, 54-60 



Organization, 11, 18 



Organ systems, 60, 116 



Origin of the germ cells, 223-242 



Origin of the individual, 209-260 



Origin of species, 345-378, 410, 411 



Osmosis, Sgj^SS, 



Osteology, 140 (see Skeleton) 



Ovary, 119, 123, 148, 203 



Oviduct, 123, 179, 205, 208 



Ovule, 110, 112 



Ovule case, 108 



Owen, 394 



Ox, skeleton of leg, 352 



Oyster, 135, 415 



Pain, sense of, 195 



Paleontology, 4, 356-364, 393 



Palm, 67 



Pancreas, 149, 152, 155, 158 



Pancreatic duct, 151, 155 



Paramecium, 39, 52, 116, 157, 169; 

 aurelia, 40, 244; behavior, 340, 

 341; calkinsi, 40; caudatum, 

 40; conjugation, 41, 245; con- 

 tractile vacuole, 40; digestion, 

 42; division, 41; ectoplasm, 40; 

 endomixis, 41, 248; endoplasm, 

 40; excretion, 43; focd taking, 

 42; gastric vacuole, 40; gullet, 

 40; heredity in, 264; irrita- 

 bility, 194; macronucleus, 40, 

 41, 245, 248; metabolism, 41^3; 

 micro-nuclei, 40, 41, 245, 248; 

 mouth, 40, 41; neuromotor ap- 

 paratus, 40; peristome, 40; 

 power of reproduction, 375; re- 

 production, 212, 246; respira- 

 tion, 43; species, 40, 414; struc- 

 ture and life history, 39-41; 

 trichocysts, 40 



Parasitism, 68, 220, 334-338 



Parencephala, 188 (see Cerebral 

 hemispheres) 



Parthenogenesis, 243, 249 



Pasteur, 210 



