INDEX 



547 



Mendel's second law, deviations from, 70 



Meristematic growth, 102, 108 



Metabolic activity in enzyme systems, 110 



Metabolic reactions, 214 



Metabolites, essential, 115, 116, 117 



Metaphase I, 78 



Metaphase I with eleven dyads, 67 



Metaphase II, 74, 75, 76, 78, 79 



Metaphase II dyads, 73 



Metaxenia, 10 



Methionine requirers, 276 



Mexican commercial corn growing areas, 



426 

 Mexican breeding stations, 426 



Mexican corns, 175-98, 418-50 

 Bolita, 427, 443, 449 

 Cacahuacintle, 420, 423 

 Celava, 427, 436, 437, 438, 440, 441, 442, 

 443, 444, 446 

 crosses between Conico Nortefio and 



Tabloncillo, 438 

 hvbrids and synthetics developed from, 

 '442 

 origin of, 436 

 Celita, 444 

 Chalco 433 434 

 Chalqueno, 418, 423, 424, 427, 431, 433, 



434, 446, 449 

 Conico, 420, 423, 424, 427, 435 

 Conico Norteno, 427, 435, 436, 438, 439, 

 443,444 



probable origin of, 421 

 Leon CrioUo, 429 

 Olotillo, 420, 423 

 Palomero Toluqueno, 420, 423 

 Tabloncillo, 427, 438, 443 

 Tepecintle, 420, 432 

 Tuxpeno, 420, 423, 424, 427, 442, 444 

 Urquiza, 429, 430, 433, 434 

 Vandeno, 427, 444, 449 

 probable origin of, 422 

 Mexican corn belt, 436 

 Mexican corn, evolution of, 419, 424, 425 

 Mexican corn improvement program, 425 

 Mexican corn program, 428, 448 

 Mexican corn races, 427 

 Mexican open-pollinated varieties, 419 

 Mexican races of maize, origin of, 176-80 

 Mitochondria, 261 

 Model heterocaryons, 210-12 

 Modifying genes in maize X teosintc, 191- 



92 

 Monoploid sporophyte, 389, 398, 399 



Monoploids 



distribution, 396 



fertility, 393, 398 



frequency of occurrence, 394-95 



in maize, 389-99 



method of isolating, 392 

 origin, 389 

 reproduction, 390 

 study of 



in the agronomic field, 390 



in the cy to logical field, 390 



in the genetic field, 390 



Morphological characters as related to 

 heterosis, 141-46 



Morphology of inbreds, technique of study- 

 ing, 141 

 Mosaic dominance, 295 

 Multiform genus, 321 

 Multiple alleles, 102, 228, 254 

 Multiple allelism, 500 

 Mutant genes, survival and growth, 235 

 Mutant strains, 214 

 Mutant, superior, 323 



Mutants, 218 



in S. typhimunum, 281 



Mutation, 103 



Mutation frequency and X-ray dosage, 



271-74 

 Mutation, random, 323 

 Mutation theory, De Vries, 20 

 Mutational euheterosis, 218-20 



Mutations 



deleterious character of, 219 

 genetic implications in S. typhimurium, 

 267-81 

 Mutations isolated and X-ray dosage, rela- 

 tion between, 273 



Native open-pollinated varieties, utilization 



of, 426-27 

 Natural populations, genetic structure of, 



152 

 Natural selection, 15, 151, 157, 219-20 

 Negative heterosis, 225 

 Neo-centric activity, 75, 77 

 Neo-centric fibers, 75 



Neo-centric regions, 72, 74 



formation of, 77 

 Neo-centromeres, arising from chromosome 



ends, 80 

 Neomorphs, 295 



Neurospora 



biochemical models of heterosis, 199-217 

 biochemical reactions essential to growth, 



120, 208-9 

 cells of, 199-201 



and higher organisms, difTerences be- 

 tween, 201-2 

 Nicking, 353, 451 

 Nicotiana hybrids, 14 



