420 



INDEX 



Ducks, birth stages in, 201 



Diijardin, Felix, 25, 2(i 



Duodenum, 117, 118, 120; digestion in, 



144 ; mucosa of, 145 

 Dyads, 211, 212, 213 



Ear, development of, 230; middle divi- 

 sion of, 226, 230; sensory cells of, 164 



Ear drum, 231 



Earthworm, 184, 185; capsule of, 192; 

 classified, 273; cocoon formation in, 

 185; copulation, 192; egg case of, 

 198; fertilization in, 191; figure of 

 dissection of, 119; rate of propaga- 

 tion, 303; reproductive organs of, 

 128 



Echinodermata, 172; classified, 269, 272 



Echinoderms, classified, 272 



Echinoidea, classified, 269, 272 



Ecology, 3, 4, 6, 275-288; methods and 

 aims, 287; relations to physiology, 

 288; relations to zoogeography, 288, 

 309; scope of, 275; in taxonomy, 267, 

 268 



Ectoderm, 65, 220, 221, 222, 223, 224, 

 225, 227; of Hydra, 94 



Ectoparasites, defined, 279 



Edaphosaurus, 332 



Edaphosaurus cruciger, 333 



Edentata, classified, 271 



Edwardsiidea, classified, 269 



Eels, freshwater, migration of, 300 



Efferent fibers, 142 



Egg, 174; blastula from telolecithal, 219; 

 centrolecithal, 214, 215; cleavage in 

 centrolecithal, 220; cleavage in 

 homolecithal, 217-218; cleavage in 

 telolecithal, 218, 219; fertilized, 211; 

 form of, 213-215; homolecithal, 214; 

 mature, 211, 213; telolecithal, 214, 

 215 



Egg carrying, 199; in crayfish, 199; in 

 frogs, 200; in Hyla fuhrmanni, 200; 

 in insects, 200; in nuirsupial frog, 

 200, 201; in mussels, 199; in pipe- 

 fish, 201; in sea horse, 201 



Egg cases, of earthworms, 198; of insects, 

 198; of leeches, 198; of snails, 198; 

 of spiders, 198, 200 



Egg laying (see Oviparity) 



Egg membrane, 214, 215, 218 



Eggs, of amphibious animals, 204; of 

 aquatic animals, 204; of aquatic tur- 



tles, 198; care of fertilized, 198, 205; 

 of digger wasps, 198; fertilized in 

 ovary, 196; of ichneumon flies, 198; 

 of insects, 195; of mammals, 195; 

 of Megapodes, 198, 199; nourish- 

 ment of, 195, 196, 197; place of 

 development of, 194, 195, 196; of 

 salamanders, 198; of sharks, 196; 

 of skink, 199, 200; of toads, 198 



Egg shell, 215 



Elasmobranchii, classified, 270, 273 



Electric current produced by glandular 

 activity, 155 



Electrolytes, 28, 41 



Elements in protoplasm, 38 



Elephant, 319, 321, 322, 323, 332, 333, 357, 

 358; African, 323; cancellate bone, 

 320; evolution of, 319-324; evolution 

 of lower jaw, 320; evolution of pro- 

 boscis, 320;incisors, 320; Indian, 321, 

 322, 323; nasal openings, 320; num- 

 ber of teeth, evolution in, 320 ; tusks, 

 320 



Elephas, 320, 321, 323 



Elodea, 50, 61 



Embryo, 206, 218, 225; development in 

 mammal, 196; homolecithal, gas- 

 trulation in, 220; place and nutri- 

 tion of, 195, 196, 197; in shark, 197; 

 telolecithal, 223; telolecithal, gas- 

 trulation in, 221 



Embryology, 2, 14, 175, 206, 206-238; 

 comparative, 337 



Embryonic development, 8, 28 



Empedocles, 8 



Empirical formula, 40 



Emulsion, 35, 36, 37 



Enamel, 322, 323, 327; in elephant teeth, 

 321 



Endoderm, 65, 210, 220, 221, 222, 223, 

 224, >225, 227 ; of Hydra, 94 



Enterokinase, 145, 146 



Enteropneusta, classified, 270, 273 



Entomologist, defined, 5, 267 



Entoparasites, defined, 279 



Environment, 21, 275; a cause of varia- 

 tion, 257; change of, 316, 317; a 

 complex, 287; dependence of ani- 

 mals on, 307; in evolution, 359; a 

 factor in distribution, 305 ; migration 

 of, 317; mutability of, 305; physical, 

 associations formed by, 277, 282, 283, 

 284; possible cause of evolution, 356; 



