INDEX 



Hybridization (Continued) 



advantageous, 477-479 



disadvantageous, 474—477 



introgressive, 479-481 



See also Heterozygotes 

 Hydra, 77,72, 151 

 Hydrogen, 79, 80. 5/ 

 Hyena, 28 



Hypohippiis. 204. 205. 409, 410 

 Hypopharynx in insects, 33, 34, 35, 36 

 Hyracolherium, 200, 201, 202, 203, 204, 

 270, 272, 409, 411 



brain of, 201,205, 236 



limbsof, 795. 200-201.202 



skuUof. 799. 201 



teeth of, 207 



See also Equiis; Horse 



Ice ages, see Pleistocene period 

 Ichthyosaurus, 15, 129, 7 77. 185-186 



convergent evolution in. 30 

 Iguana, marine, 289 



terrestrial, 289, 290, 291 

 Immigration, see Dispersal, means of; 



Migration 

 Immortality, belief in, 244 

 Immunity, 109 

 Implements, see Tools 

 Impression, fossil, 129 

 Inaccessibility, 265-267 

 Inchofer, Father, 510 

 Infusoria, 73 

 Inghram, M., 138, 142 

 Inheritance, mechanisms of, see Mende- 



lian inheritance 

 Inner cell mass, 5 1 , 52 

 Insect, 137, 147,446 



beaks of, 35, 36 



courtship behavior of, 472, 493 



excretion by, 94 



of Hawaii, 286, 490 



mimicry in. 373 



mouth parts of. 33, 34, 35, 36, 40 



Pennsylvanian, 164-765 



Permian, 166-167 



preservation of, 129 



proboscis of, 35, 36, 40 



reproductive isolation of, see Isolation, 

 reproductive 



social, 137,355 



transportation of, 284—285 



wings of, see Wings 



See also Ant; Bee; Drosophila; 

 Fossils 

 Insectivora, 192, 195, 220, 221, 504 



arboreal, 505 

 Interbreeding, see Hybridization 

 Interglacial period, 195 



539 



Intergradation, areas of, 520-321 

 Inversion, 336, 597-398, 460 



experimental, 398 

 Invertebrates, homology in, 33-36 



See also Animals 

 Invertebrate-vertebrate relationships, bio- 

 chemical evidence of, 100-103 

 Iris, hybrid, 479 

 Irish stag, extinction of. 41 1 

 Iron ore. 145 

 Irradiation, see Radiation and mutation 



formation 

 Island-hopping, 120,266 

 Islands, continental, 270, 280 

 "floating." 285-286 

 and founder principle. 446 

 oceanic: defined, 280: dispersal to, 

 284-287; nature of, 281-282; popu- 

 lation of, 282. 445, 485, 488, 490 

 volcanic. 28I-2S2 

 young, 286-287 

 Isolation, 469-474 

 action of. 473-474 



biological, see Isolation, reproductive 

 of breeding groups, 469-470 

 environmental, 470-471, 473-474, 478, 



485. 489 

 geographic, 265-267. 270, 293, 418, 

 445, 469-470, 471, 473-474, 485, 

 489 

 mechanical, 471-472 

 reproductive, 248, 250, 314-317, 318- 

 319, 321, 418. 420. 471-473, 474, 

 476, 485-486, 487-489, 493 

 sexual, see Isolation, reproductive 



See also Barriers; Isolation, re- 

 productive 

 Isometric growth, see Allometry 

 Isotopes. 138-140 

 Ives, P. T., 501,507 

 Ivory, 209 



James Island, 289 



Java man, see Pithecanthropus 



Jaw, of apes, 230-232 



of australopithecines, 234 



of birds. 188 



of chimpanzee. 257 



of Cro-Magnon man. 245 



of elephant, 215-216 



of Gomphotherium, 213, 215, 216 



Heidelberg. 240 



of Homo sapiens, 230-232 



of humans, embryonic. 59 



of mammals, 172, 190 



of mammoth, 215-216 



of mastodon, 213-214 



of Moeritherium, 210-212, 216 



