Subject Index 



581 



Crossing over (continued) 

 in an inversion, 397, 398, 399, 400, 



402 

 in four-strand stage, 206 

 in male Drosophila, 152, 154, 162 

 in plants, 154, 157 

 in ring chromosomes, 396 

 not more than 50 per cent, 178, 



211 

 percentage of, 150, 152, 153, 154, 

 155, 157, 158, 159, 160, 166, 

 171, 176, 177, 178, 211 

 relation of to chiasmata, 152, 153, 



202 

 somatic, 216, 217 

 use of in locating genes on chro- 

 mosomes, 171 

 Crossover suppressor, 252, 255, 256, 



402 

 Cross-sterihty classes, 271, 273, 274, 



275, 276, 277 

 Cucurbits, 315, 316 

 Cumulative genes, 331, 332, 343, 345, 

 353, 354, 357, 358, 371, 372, 

 385 

 Cycadales, 440 

 Cytogenetics, 2 

 Cytological map, 191, 193 

 Cytology, 1 

 Cytoplasm, 3, 4, 5, 6, 9, 10, 12, 78, 



540, 542 

 Cytotaxonomy, 2, 438 



Dactylis glomerata, 435, 453 

 Dahlia variabilis, 430 

 Datura, chromosomal chimeras in, 

 478 

 embryo culture in, 524 

 haploids in, 437 



reciprocal translocations in, 405, 

 407, 408, 409, 534 

 Datura inoxia, 524 

 Datura Stramonium, induced muta- 

 tions in, 243 

 trisomies in, 419, 420, 421, 423, 430 

 Deficiency, 27, 250, 390, 391, 392, 

 393, 394, 414, 427, 428 

 behavior of at meiosis, 394 



Deficiency {continued) 

 origin of, 393 



X-ray induced, 392, 393, 394, 395 

 Deletion, 55, 193, 194, 390, 393. 395 

 Delphinium, 237, 238, 239, 240 

 Development of the individual, 301, 



302, 303 

 Diakinesis, 14, 54, 58, 417, 448 

 Dicentric chromosome, 396, 397, 398, 



399, 400, 401, 442 

 Digitalis, 458 

 Dihybrids, 127, 142, 320 



modified ratios in. 321 ff. 

 Dioecious plants, 503 ff. 

 Dioscorea sinuata, 505 

 Diploid number of chromosomes, 



49, 53 

 Diploids, production of from hap- 

 loids, 477 

 size in, 449, 450, 4ol 

 Diplotene, 54, 56, 57. 58, 65, 418, 



446, 447 

 Discontinuous variation, 346. 358 

 Dissosteira Carolina, 134 

 Dominance, reversal of, 88 

 Dominant genes, 19, 20. 105 

 Double cross method of breeding 



hybrid corn, 387, 3S8 

 Double crossing over, 173, 174, 175, 

 177, 178, 179, 180, 210, 211, 

 212, 213 

 Double nature of chromosomes, 52, 



53, 55, 56, 59, 63 

 Drosophila, crossing over in. 167 

 isolating mechanisms in, 523 

 lethal effect of homozygous trans- 

 locations, 404 

 terminal deficiencies in, 391 

 triploids in, 440, 450 

 Drosophila funebris, abnormal ab- 

 domen, 33 

 heterochromatin in, 223 

 Drosophila hydei, heterochromatin, 



in, 222 

 Drosophila melanogaster, attached- 

 X, 248 

 autosomes in, 70, 506 



