One ml of E.coli is mixed with 1ml of dye. A drop of this dilution is placed on a Petroff-Hausser counting chamber. Five large, double-lined squares, each containing a volume of 1/1,250,0000 cc, are counted giving the following results: 61, 74, 78, 63 and 64 bacteria. How many bacteria are there per cc in the original sample?

Microbiology Laboratory Manual by Gary E. Kaiser, PhD, Professor of Microbiology
is licensed under a Creative Commons Attribution 4.0 International License.
Last updated: August, 2017