Subject Index 



587 



Hj^brid corn, 378, 387 

 Hybrid embryos, culture of, 524. 525 

 Hybrid index, 528. 529, 530 

 Hybrid swarm, 518. 519, 521, 523, 



524, 526, 527, 536 

 Hybrid vigor, 384. 385. 388 

 Hybrids, abnormal development of 

 endosperm in, 443, 444, 445 



chromosomal, 518 



gene, 517 



in cattle, 382 



in maize. 384 



intergeneric, 459, 4^0, 4^1 



interspecific, 517, 530. 531, 532. 533 



in Tradescantia, 400, 519, 520, 525, 

 526, 527, 528 



intraspecific. 517 



mendelian, 517. 518 



sterility of, 456. 459, 467, 531, 532 

 Hj'bridization, introgressive, 526, 



528 

 Hypostatic genes, 321 



Imperfect flowers, 503, 510 

 Inbreeding, 367 ff., 539 



beneficial effects of, 368, 369 

 harmful effects of, 367, 373 

 in animals, 373 

 in maize, 367, 384, 387 

 Incomplete dominance, 22. 86. 87. 

 88, 130, 131, 332, 336, 343, 344, 

 345, 353, 357, 358, 371, 372 

 Incomplete sex linkage, 95, 106 



in man, 196, 197 

 Independent assortment, law of, 



126, 137, 139, 147, 166 

 Independent events, probability of 



occurrence of, 110. 179 

 Index frequencies for comparing 

 populations, 525, 526, 527, 528, 

 529, 530, 531 

 Indole-3-acetic acid, 478 

 Inert regions, 190, 192, 220, 267 

 Inhibiting genes, 325, 326, 327 

 Insanity, heredity of, 37, 38 

 Insects, 522 



embryology of, 496, 497 



Interaction of genes, 23-26, 304, 



320 ff., 342 ff. 

 Interference, 179 

 Interkinesis, 62, 63 

 Intersexes, 482 ff., 493, 497, 513 

 Introgressive hybridization, 526, 528 

 Inversion, as crossover suppressor, 

 168, 252, 255 



crossing over within, 397, 398, 399, 

 400, 402 



independent, included, and over- 

 lapping, 402 



pairing in at meiosis. 55, 193, 194. 

 397 ff., 398, 399, 414 



X-rays and, 394, 399 

 Iris, 10, 520, 521, 525 

 Isolating mechanisms, 516. 518. 519 

 Isolation, ecological, 519, 522 



gamete-incompatibility, 523 



gene-cytoplasm. 523 



geographic. 519 



hybrid lethality, 523 



hybrid sterility, 524, 531, 533 



mechanical, 522 



psychological, 522, 524 



seasonal, 521, 522 



sexual, 522 



Karyokinesis, 6 

 Karyolymph, 6 

 Karv'osome, 486 

 Karyotype, 532, 533 

 Kinetochore, 7, 125 

 Kynurenic acid, 308 

 Kynurenin, 308, 309 



Lagging at meiosis, 416, 442 

 Lampbrush chromosomes, 78 

 Lathyrus odoratus, round vs. long 

 pollen, 163 

 number of chromosomes in, 187 

 number of linkage groups in, 187 

 purple flowers, 163, 326, 327, 328 

 Leptotene, 53, 54, 64 

 Lethals, 101, 200, 231, 245, 250-257, 

 386, 427, 428 

 balanced, 534, 536, 537 



