Oo2 



INDEX 



and sensory, 162, 169, 334; 

 sciatic, 62, 162, 515; spinal, 

 160, 409, 445, 515, 568 ; sym- 

 pathetic, 162, 445, 516; vaso- 

 motor, 174 ; visceral, 366 

 Nervous impulse, 62, 154 , 

 Nervous system : Frog, 155; Hydra, 

 298 ; Bougainvillea, 311; Earth- 

 worm., 333 ; Crayfish, 365 ; Mus- 

 sel, 392 ; Lancelet, 404, 408 ; 

 Dogfish, 442; Rabbit, 511 ; de- 

 velopment of, in Vertebrates, 565, 



Neural arch, spine, and canal, see 

 Vertebra 



Neural plate and process, 424 



Neuraxis, 167 



Neurenteric canal, see Canal 



Neurilemma, 167 



Neuroccele, 443 ; and see Canal, 

 central of spinal cord, and Ven- 

 tricles of brain 



Neuroglia, 169 



Newt, 218 



Nictitating membrane, 5, 469 



Nodes of nerve-fibre, 167 



Nose, see Olfactory organ 



Nostrils, 5, 17, 180, 416, 448, 468, 

 470. 517 



Notochord, 203, 404, 425, 560, 

 576, 5S7 



Nuclear division, 544, ^8$ ; in- 

 direct, 545 



Nuclear membrane, 542 ; spindle, 

 544 



Nucleolus, log et set/., 541, 542 



Nucleus, 106 et sei/., 129, 231, 243, 

 254, 265, 269, 273 



Nucleus, conjugation-, 268 ; seg- 

 mentation-, 554 



Nutrition, 67 ; and see under various 

 types 



o. 



o 



"belia, 317 

 Occipital condyle, see Skull 

 Ocellus, see Eye-spot 

 Oesophagus, see Gullet 



Odontoblasts, 429 

 Odontoid process, 4S2 

 Olecranon, 49, 485 

 Olfactory capsule, 39, 42, 420, 476 

 ,, lobe, 160, 444, 511, 514, 



568 

 ,, organs : Fro^, 180 ; Cray- 

 fish, 367 ; Mussel, 394 ; Dogfish, 

 416, 448; Rabbit, 511, 517; de- 

 velopment of, in Vertebrates, 569 

 Olfactory pit, 408 

 Oligochieta, 341 

 Ommatideum, 366 



Ontogeny, 224 



Oogenesis, 196, 548 



Oosperm, 198 ; and see under 

 various types 



Oosperm, holoblastic and mero- 

 blastic, 556 



Opalina : occurrence and general 

 characters, 269 ; structure and 

 division of nuclei, 269 ; parasitic 

 nutrition, 271 ; reproduction, 

 271 ; means of dispersal, 272; 

 development, 254 j practical di- 

 rections, bSj 



Optic chiasma, see Chiasma ; cup, 

 570 ; lobe, 157, 443, 513, 566 ; 

 thalamus, 159; vesicle, 569 



Oral cavity, see Buccal cavity 



Oral hood, 406 



Orbit, see Skull 



Order, 218 



Organ, 30, 151, 238, 335 



Organism, 231 



Origin of muscles, 60 

 ,, of species, 225 



Osmosis, see Diffusion 



Osphradium, 394 



Ossicles : ai ^\zz&\A.(Crayfish). 358, 

 376; -iwd^Aoxy [Rabbit) , see Audi- 

 tory ossicles 



Ossification, 44 



Ostia : of heart, 362 ; of gills, 389 



Otocyst, 394 



Otoliths, 188 



Ovary : Frog, 23, 193, 195 ; and see 

 Reproductive organs 



Oviduct, 25, 196, 337, 368, 453, 

 523. 574 



