A higher plant has between one and ten million genes, each of which holds information that specifies the structure of a product RNA and, often, a protein. In addition, each has nucleotide sequences involved in recognizing on-off signals. Using recombinant DNA technology, pieces of DNA carrying one or a few genes can now be removed from practically any organism, replicated in microorganisms, and then studied at the level of nucleotide sequence and sequence arrangement. A few genes from higher plants are now being analyzed at this level, and alcohol dehy-drogenase-1 (Adhl) in maize, the gene studied most intensively in my laboratory, is one of them.