The chromosome theory as illustrated by the genetics of neurospora. Outline of the biology of fungi of genetic interest. The induction, isolation and characterization of mutants. Chromosome mapping-meiotic analysus. Genetic analysis based on mitosis. Polyploidy. The gene as a functional unit. The mechanism of genetic exchange and the fine structure of genes. The genetic control of metabolism. The genetic control of macromolecular structure. Systems of regulation of enzyme synthesis. The genetic control of sexual development. Extra-nuclear inheritance.