Abstract
Some 50 years of increasingly intense genetic study had not prepared molecular biologists for the recent and entirely unexpected discovery that genes in higher organisms are encoded in discontinuous bits and pieces of chromosomal DNA.1 2 3 4 5 6 7 8 These new genetic facts now force us to reformulate the comfortable notion of "one gene — one polypeptide chain" and substitute for it the more awkward aphorism, "several gene segments — one polypeptide chain." But even with this revision, the end of such changes may not be in sight.Although evidence of genes in pieces is quickly accumulating from life forms ranging from viruses and . . .