The first wave of genetic revolution involved study of the structure of the deoxyribonucleic acid (DNA) molecule. This new insight into the mysteries of heredity quickly led to another revolution. In the early 1970s, scientists discovered unique ways to manipulate genes. This technology, known as ligation, has generated scores of studies. The methods involve copying, dissecting, modifying, and even recombining portions of DNA from different sources. More importantly, these foreign genes can be made to become an integral part of the bacterium. They will replicate along with the original genes just as if they had always been a part of the bacterial cell. Thus, when the genetically altered bacteria replicate, the spliced genes are transmitted from one bacteria to the next. The foreign genes can also be functional within their bacterial host. They can be introduced to make their normal gene products. The substances secreted by altered bacteria...