Index 



735 



Thyroid, progressive increase of 

 iodine compounds in, 575, 

 581 

 reciprocal action on anterior 



pituitary, 584, 585 

 selective affinity for iodine, 



575 

 thiouracil inhibition of, 633 

 vascularity of, 581 

 Thyroid hormone, action on neu- 

 ral elements, 389 

 Tissue culture, 352, 356, 358, 360, 

 367, 381 

 axon outgrowth in, 350 

 Tissue interaction, 113 

 Tooth, abnormalities in, 495, 496, 

 497 

 appositional calcification of, 495 

 appositional growth of, 495- 

 497 

 formative span of, 496-497 

 potential for, 496 

 rates and gradients of, 496 

 attrition of, 497 

 calcification of. 497 

 components of, 492, 494 

 developmental stages of, 492, 



493 

 eruption of, 497 

 germ of, 494 

 growth of, 492-497 

 growth centers of, 496 

 incremental cones of, 496 

 initiation of, 492, 494 

 life cycle of, 492 

 morphodifferentiation in, 495 

 organogenesis of, 492-498 

 Tooth germ, 494 



enamel organs of, 494 

 initiation of, 455 

 morphodifferentiation in, 495 

 odontoblasts of, 494 

 "Towing," 351, 356, 361 

 Transcendentalism, 9, 14, 17 

 Transneuronal effects, 383 



Transplantation of cornea, 385 

 of eyes, 358 

 heterotopic, 361 

 of limb buds, 358, 359, 361 

 of M-cell region, 379 

 of nasal placodes, 358 

 xenoplastic, 263-265 

 Tubularia regeneration, competi- 

 tion hypothesis in, 670- 

 671 

 correlation in, 668 

 electrical potentials in, 668- 



669 

 inhibition of, 666, 667, 668, 



669, 670 

 polarity in, 665 

 respiratory rate in, 672 

 stimulus for, 666 

 temperature as factor in, 

 671 

 Tumor agent, 381 

 Tumor transplantation, 381 

 Tumors, 708, 709 



innervation of, 362 

 Tunicates, progressive differenti- 

 ation in, 321-323 

 Turgor, 371, 372, 374 

 Twinning, 127 



of amphibian egg. 127-128 



in annelids, 325 



in bird blastoderm, 306 



in insects, 338 



of kidney, 469 



in sea urchin, 327 



in teleosts embryos, 304 



species differences in, 711, 

 712 

 "Two-center effect," 354, 358, 359 

 Type specificity, 380 



Urinogenital sinus and cloaca, 

 reactions to sex hormones, 481- 

 482 



Urinogenital system, organogene- 

 sis of, 462-491 



Vascularization of neural tube, 

 375 



Vegetalization of entire eggs, 329 

 graded intensity in, 329 

 hypotheses to account for, 330- 



331 

 in sea urchins, 327-331 

 time required for, 328 

 in vegetative halves, 327, 328, 

 329 



Virus as teratogenic agent, 702, 

 714 



Visceral asymmetry. See Situs in- 

 versus. 



Vital staining, 234 

 value of, 32 



Vitamin deficiencies as terato- 

 genic agents, 701, 712 



Wallerian degeneration, 349 

 Wing bud, essentiality of ecto- 

 derm for, 437, 438 

 fate maps of, 437 

 sequential order of parts of, 

 437 

 Wingless mutant, 706, 707 

 "Wink" reflex. 389 

 Wolffian lens regeneration, 410- 



412. 690-692 

 Wound healing, epithelium in, 

 689-690 



Xenoplastic inductions, 246, 280 

 Xenoplastic transplantations, 263- 



265 

 X-irradiation, effect on developing 

 CNS, 373 

 in teratogenesis, 715 

 sensitive periods to, 713 

 as teratogenic agent, 701, 709, 



710 

 treatment of gametes by, 711 



Yolk utilization in development, 

 527 



