INDEX 



631 



Hydrozoa, 145 

 Hyenas, 434, 436 

 Hygiene, 6, 520 

 Hyla versicolor, 373 

 Hymenoptera, 292, 296 

 Hyoid arch, 382 

 Hypermetamorphosis, 286, 479 

 Hypertrophy, 293 

 Hypodermis, 236, 244, 465 

 Hypomere, 478 

 Hypopharynx, 278 

 Hypophysis, 317, 408 

 Hypostome, 136, 139 

 Hyracotherium, 553 



I-beam principle, 406 



Ibex, 535 



Ice fish, 362 



Icerya purchasi, 294 



Ichneumon flies, 296 



Ichthyology, 5 



Ichthyophis, 373 



Ichthyosaurus, 474 



Identical twins, 568 



Idiacanthus ferox, 363 



Idiosyncrasy, 517 



Iguanas, 392 



Ileum, 328, 547 



Iliac artery, 345, 428 



Iliac vein, 345, 428 



Ilium, 327, 400 



Imago, 286 



Immunity, 519-520 



Impulse, nervous, 103, 243 



Inbreeding, 563, 564 



Incisors, 425 



Income and outgo, organism, 458 



Incomplete dominance, 563 



Incomplete metamorphosis, 284, 286 



Incubation, 420 



Incurrent canals, 132 



Incus, 336, 337, 428 



Independent effectors, 496 



Indirect response, 57 



Individuality, 460, 481, 517 



Infection, 517 



Infective organisms, 517 



Infertile females, 296 



Infusoria, 7, 83, 84, 88 



Ingestion, 33, 35, 65, 104, 358-359, 374-375 



Inheritance, abnormalities, 564 



acquired characters, 545, 564 



diagram, 668 



disease, 516, 564 



in guinea pig, 559, 660 



in organisms, 555-569 



small eyes, 566 



tapering fingers, 566 

 (See also Genetics) 

 Inherited immunity, 519 

 Ink sac, 226 

 Inner cell mass, 445 

 Inner chamber, eye, 338, 339 



Inner ear, 336-338, 347, 360 



Inorganic matter, 17 



Insanity, inheritance, 564-566 



Insect powders, 294 



Insecta, 276-301, 311 



Insectivora, 426, 429 



Insects, 276-301, 310, 501, 506, 509, 533, 538, 



542 

 Insertion, muscle, 471 

 Inspiration, 33, 34, 36, 71, 491 



(See also Respiration) 

 Instars, 284 

 Instinct, 263, 305, 311, 361, 375, 377, 498-600, 



503 

 Integration, 459, 475 

 Integument, 324 



(See also Skin) 

 Intelligence, 305, 311, 361, 377, 501-504 

 Interaction of genes, 562 

 Interambulacral plates, 207 

 Interambulacral rows, 206 

 Intercellular differentiation, 95 

 Interlamellar junctions, 215 

 Intermediate hosts, 172 

 Internal anatomy, birds, 406-409 



crayfish, 258-259 



ctenophores, 156-157 



earthworm, 234-239 



fishes, 356-358 



flat worms, 172 



hydra, 137 



insects, 281-282 



mammals, 424—429 



mussel, 215 



planaria, 159-163 



reptiles, 388-389 



roundworms, 178 



shark, 345-347 



spider, 303-304 



sponges, 130 



starfish, 196-198 



vertebrates, 322-323 

 Internal gills, 380 

 Internal inspiration, 36, 37 

 Internal secretions, 373, 459, 492 

 Internal skeleton, 313, 322 

 Internal structure (see Internal anatomy) 

 International Commission on Zoological Nomen- 

 clature, 573 

 Interoceptors, 473 

 Interradial septum, 198 

 Interradii, 195 



Interstitial cells, 138, 142, 470 

 Intertidal fauna, 511 

 Intestinal worms, 168, 170, 171, 178, 181-183. 



525 

 Intestine, 179, 214, 236, 258, 282, 346, 489 



(See also Alimentary canal) 

 Intracellular differentiation, 86, 95 

 Intussusception, 18, 27, 65 

 Invagination, 121, 237, 321, 477 

 Invertebrates, 119, 540 

 Involuntary muscle tissue, 102 

 Involuntary muscles, 327 

 Iodine, 20 



