Penicillin, Past, Present And Future -- The tubes of clear diluted Penicillin to which one drop of suspension of staphylococcus has been added to left to incubate at blood heat overnight. If the Penicillin is strong enough to kill the staphylococcus then the tubes should remain clear. If tubes are slightly cloudy, laboratory workers know more Penicillin is required. Fourteen years ago, Professor Fleming of the Chair, of Bacteriology at London University discovered that the mould Penicillium Nota