PENCILLIN

                  It is one of the most important medical discoveries of our time, for it allows doctors to easily treat illness and infections that once killed many people. If it were not for pencillin and other drugs like it, there would be little a doctor could do for you, if you came down with a very bad cold or a serious infection.

                    Centuries ado, mold bread was sometimes used as an antiseptic, but no one knew why mold kill germs. Late in the 19th century, scientists discovered that certain molds and bacteria produces substances that would kill or prevent the growth of other bacteria. These substances are now called antibiotics.
                  
                  Then, in 1928, an English scientist named Alexander Fleming was working in his laboratory with a culture of bacteria. When a kind of mold, called penicillium, accidentally infect the culture, Fleming noticed that the mold killed the bacteria around it. Further experiment showed that these molds produced a substance that would kill many common bacteria and Fleming named the substance Penicillin.

                 What was most important about penicillin was that it did not harm living body cells, as did the antibiotics discovered before that. In 1939, other scientist found a way to purify and strengthen penicillin, and it became available in the 1940s.