INDEX 



415 



Elephas, 336, 339 



tooth of, 338 

 Embryo, orientation of, 217 



source of nourishment of, 183 

 Embryonic development, 73, 193-220 



problems of, 216-220 

 Empedocles, 2, 16 



Endocrine glands, human, 153, 1.54-158 

 Endoderm, 101, 204, 206, 207, 208, 209, 

 210, 211 



of Hydra, 71, 72, 73 



organs from, 207 

 Endoskeleton, 90 

 Energy, 37 



derived from oxidation, 48, 49 



release of, 113, 119, 120 



requirements of, 108 



source of, 100-108, 113 

 Enterokinase, 105 

 Enteron, 80, 172 

 Enteropneusta, 276, 278 

 Entomologist, 257 

 Environment, 281-306 

 Enzymes, 41, 42 

 Eocene, 330, 335 

 Eophippus, 339 



skull of, 340 



tooth of, 340 

 Epithelial cells, in Hydra, 72 

 Epithelial tissue, 81, 83 

 Epoch, in paleontology, 329, 330 

 Equation division, 194 

 Equatorial cleavage, 201 

 Equatorial plate, 66, 57 

 Equus, 342 



Era, in paleontology, 329, 330 

 Erepsin, 105 

 Ergosterol, 112 

 Esophagus, of earthworm, 101, 102 



of frog, 102, 103 



of mammal, 101 



of man, 103 

 Estrogen, 156 

 Eudorina, reproduction of, 161 



spheroid colony in, 68, 70 



symmetry of, 78 

 Euglena, 260 



flagellum of, 53 

 Eustachian tube, 211 



origin of, 214 

 Evagination, 207 



Evolution, 16-18, 349-368 



of breeding habits, 185 



a change of species, 307, 352 



direction of, 358-365 



evidences of, 349-352 



human, 367, 368 



lines of, 334-348 



relation of, to distribution, 307-309 



shown by fossils, 331-348 

 Excretion, 46, 50 



by kidney, 137 

 Excretory system, 133-139 



human, 137 



of invertebrates, 134. 135 

 Exoskeleton, 90 

 Extensor muscle, 94 

 External respiration, 114 

 Extinction, 289 

 Eye, in embryo, 213 



F,, 226 



Fo, 226 



Family, 247, 248, 250 



Fats, 41 



Feather star, 267 



Femur, 93 



Fertilization, 163, 165, 167, 168 



entrance of sperm in, 217 



methods of ensuring, 179-182 



time and method of, 200 

 Fetus, 184 

 Fibrin, 130 

 Fibrinogen, 126, 130 

 Fibula, 93 

 Fishes, 277 



evolution of, 335 

 Fission, 169 



multiple, 170 

 Flagella, 52, 53 

 Flagellated epithelium, 84 

 Flame cell, 134 



Jlatworm, nervous system of, 141, 142 

 Flexor muscle, 94 



Flints, used by Neanderthal man, 346 

 Fluke. 265, 266 

 Flying squirrels, distribution of, 313, 314, 



315 

 Follicle, 156-158 

 Food storage, 107 



