We will now discuss one way to generate a growth curve using the standard curve relating absorbance and viable count. Typically to generate a growth curve a microbiologist inoculates broth with the organism he/she desires to study. The flask containing the broth is placed in an incubator (usually a shaking incubator). At set time intervals, an aliquot is withdrawn from the culture, and the absorbance of this aliquot measured at 640 nm. Using the standard curve, the number of cells at each time period is determined. A flask of E. coli Hfr was inoculated and incubated with shaking for nine hours. At half hour intervals, the absorbance was measured. The following results were obtained. Note that starting at 6.5 hour, the culture had to be diluted in order to read on the spectrophotometer. To do this, 1 ml of culture was mixed with 1 ml of uninoculated medium.