CONTENTS 



*1 Genetic Material 7 



*2 Gene Segregation 8 



*3 Mitosis 16 



*4 Meiosis 23 



*5 Segregation in Man — Multiple Allelism 32 



*6 Independent Segregation 39 



7 Gene Interaction and Phenotypic Expression 49 



8 Gene Interaction and Continuous Traits 56 



9 Multiple Alleles and Lethals 62 



10 Pleiotropism, Penetrance and Expressivity 68 



11 Studies of Human Twins 74 



*12 Sex-Linkage 81 



13 Sex Determination (I) 94 



14 Sex Determination (II) 100 



*15 Intergenic Linkage Ill 



*16 Crossing Over and Chiasma 116 



*17 Gene Arrangement and Chiasmata 128 



*18 Changes Involving Whole Genomes and Single Whole Chromosomes 137 



*19 Structural Changes within Chromosomes 150 



20 Cytogenetics of Oenothera 162 



21 Natural and Induced Chromosomal Changes 173 



11 Position Effect and Allelism in Drosophila 185 



*23 Gene and Point Mutations 197 



24 Point Mutants — Their Detection and Effects in Individuals 204 



*25 The Genetic Control of Mutability 213 



26 The Gene Pool in Cross-Fertilizing Populations 224 



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