While working with Staphylococcus bacteria in 1928, Sir Alexander Fleming accidently dropped some bread crumbs on one of the dishes. After a week the bacteria on this dish did not grow as expected. Fleming noticed a bacteria-free circle around a mold that was contaminating the staphylococcus culture. Instead of throwing the dish away because the planned experiment had failed, he isolated the mold, grew it in a fluid medium, and discovered a substance that prevented growth of the bacteria even when it was diluted 800 times. Discuss the discovery of penicillin using the terminology and issues introduced in this chapter.