a rapid method for the quantitation of various live cell types is described . this new cell fluorescence method correlates with other methods of enumerating cells such as the standard plate count , the methylene blue method and the slide viability technique . the method is particularly useful in several applications such as : a ) quantitating bacteria in milk , yogurt , cheese , meat and other foods , b ) quantitating yeast cells in brewing , fermentation and bread making , c ) quantitating mammalian cells in research , food and clinical settings . the method is especially useful when both total and viable cell counts are required such as in the brewing industry . the method can also be employed to determine the metabolic activity of cells in a sample . the apparatus , device , and / or system used for cell quantitation is also disclosed .