224 



IXDEX. 



115; non-medullated, 115; white, 

 "5 



Nerve-fibrils, the, 86; processes, 

 the. 114 



Nervous system, the, 44; develop- 

 ment of, 145; its relations to the 

 skin, 148; types of diffuse, 146; 

 ganglionic, 146; ladder, 147; lin- 

 ear, 146; tubular, 148; tissue, 87, 

 113, 117; elements of, 113; func- 

 tion of, 113 



Nomenclature, the binomial, n 



Notochord, 47 



Nuclear division, probable signifi- 

 cance of direct and of indirect, 84; 

 spindle, 82, 83; substance, 79 



Nuclei, various forms of, 78 



Nuclein, 80 



Nucleoli, 79-80 



Nucleolus, 97 



Nucleus, 97; behavior during di- 

 vision, Si; physiology of, 116; 

 significance of, So; structure of, 

 79; substance of, 79 



Nucleus of the cell, 78, 116 



Nutrition, 77, 157 



CEcology, 63 



(Esophagus, 127 



Oken, 26 



Olfactory cells, 151; tubules, 151; 



cones, 151 

 Ontogeny, 4, 193; summary of the 



facts of, 195 

 Optic ganglion, 154 

 Organ, an, change of function of, 



119; defined, 118; effect of use 



and disuse, 119; principal and 



accessory tissues, 118 

 Organology, summary of, 156 

 Organisms, origin of, 165 

 Organs, systems of circulatory, 



121 ; digestive, 120; excretory, 



121 ; genital, 121; muscular, 121; 



nervous, 121; respiratory, 120; of 



sense, 121; of smell, 150 

 Oriental region, the, 215 

 Origin of species, Darwin's theory 



of, 30 



Ora serrata, 156 

 Organic bodies, 158 

 Ossein, 103 

 Osteoblasts, 105 

 Otoliths, 99, 151 

 Outlets of sexual glands, 140; 



products, 143 

 Ovary of a new-born child, section 



through the, 95 

 Oviduct of an insect, 96 



Oviducts, 143 

 Oviparous, 194, 198 

 Ovo-viviparous, 194, 198 

 Owen, 21 

 Oxidation, 123 



Oxygen, sources of, used in breath- 

 ing, 128 



Pacinian corpuscles, 150 

 Ptedogenesis, 170, 196 

 Paljearctic region, the, 214 

 Paleontology, 5-25 ; proofs of 



phylogeny from, 39 

 Paleontological proof, examples 



f. 39 



Paleozoology, 5 

 Pancreas, 127 

 Paranuclein, 80 



Parasitism, 202; degeneration 

 caused by, 203; modification of 

 sexual apparatus by, 203; true, 

 202 



Parthenogenesis, 170, 196 

 Penis, 144 



Pentastomum taenioides, 204 

 Perennibranchiata, 43 

 Pericardium 133 

 Periosteum, 104 



Peripheral nervous system, 146 

 Peritoneum, 132 

 Pharynx, 127 



" Philosophic zoologique," 26 

 Phylogeny, 5, 36; proofs of 38 

 Physiology, 4; biology, 5; expla- 

 nation of the organic bodily 

 form, 4, 5; life, 4; cecological 

 problems, 5; oscology, 5; vital 

 process, the, 4 

 Physiologus or Bestiarius, the, 



10 



Pieridee, 57 



Pigment-spot (simplest eye), 153 

 Plankton, the, 216 

 Planula, 145, 193 

 Plasmodia, 73 

 Pliny, 9 



Poikilothermous animals, 137 

 Polar bodies, formation of, 176 

 Polymorphism, 200 

 Polyspermy, 178, 179 

 Porto Santo, the rabbits of, 63 

 Post-Darwinian writers, 29 

 Post-embryonic development, 192 

 Praya diphyes, 201 

 Proctodoeum, 125 

 Progression, Nageli's principle of, 



65 



Promorphology, 158 

 Prostoma, 187 



