224 



INDEX. 



115; non-medullated, 115; white, 



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, 80; structure of, 



79; substance of, 79 

 Nucleus of the cell, 78, 116 

 Nutrition, 77, 157 

 CEcology, 68 

 Oesophagus, 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, I2o;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 

 Paedogenesis, 170, 196 

 Palaearctic region, the, 214 

 Paleontology, 5-25 ; proofs of 



phylogeny from, 39 

 Paleontological proof, examples 



of, 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 tasnioides, 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; cecology, 5; vital 

 process, the, 4 



Physiologus or Bestiarius, the, 

 10 



Pieridae, 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 



Proctodceum, 125 



Progression, Nageli's principle of, 



65 



Promorphology, 158 

 Prostoma, 187 



