Genetic engineering, scientific discipline of altering or combining the genes in a living organism, first developed in the 1970s. This is accomplished through the manipulation of DNA, which is the primary component of the heredity-controlling chromosomes. In order to genetically alter an organism, a particular gene must be isolated through a process known as gene splicing, which permits the transference of a gene from one species to another. The scientific objective of genetic engineering is its enormous potential application in the fields of medicine, agriculture, and business. In medicine, the use of gene therapy may be an important new development in the treatment of diseases. Genetic engineering offers the possibility for the elimination of genetic defects. In industry, genetic engineering may be used to eliminate environmental hazards because certain genes can detoxify dangerous elements. In agriculture, healthier and stronger animals can be produced. Genetic engineering does, however, have a controversial side. Environmentalists fear that some accident or misapplication might produce devastating consequences. The moral implications of how human reproduction might be affected is a very important issue in the field. To this end, the National Institute of Health has issued guidelines (1976, 1985) that control many procedures.