Clone is an organism, or group of organisms, derived from another organism by an asexual (nonsexual) reproductive process. The word clone has been applied to cells as well as to organisms, so a group of cells stemming from a single cell is also called a clone. Usually the members of a clone are identical in their inherited characteristics-that is, in their genes -except for any differences caused by mutation. Identical twins, for example, who originate from the division of a single fertilized egg, are members of a clone; whereas non-identical twins, derived from two separate fertilized eggs, are not clones.
             Through recent advances in genetic engineering, scientists can isolate an individual gene (or group of genes) from one organism and grow it in another organism belonging to a different species. This technique is called cloning because it uses clones of organisms or cells. It has great economic and medical potential and is the subject of active research ("Clone").
             The idea of cloning came about in the early 1900's. A German scientist named Hans Spemann first thought of the cloning methods around 1938. One of the first attempts on cloning, however, was by a scientist named Adolph Eduard Driesch. He shook a flask that contained sea urchin eggs so the eggs would separate and grow. After unsuccessful attempts to grow these separate eggs, Driesch lost hope and gave up. Nevertheless, the study continued. In the great city of Philadelphia in the year 1952, two biologists named Robert Briggs and Thomas King developed a cloning method called nuclear transfer. In nuclear transfer, the DNA is removed from an unfertilized egg, and the nucleus of a specially prepared body cell is introduced. The combination or "couplet" is triggered either by an electrical pulse or the introduction of a chemical to fuse them together and begin the process of development. Nuclear transfer was first attempted on the eggs ...