An improved technique for counting leucocytes in milk by the direct microscopic method.

An improved microscopic method for counting leucocytes in milk has been developed, which results in acceptable levels of reproducibility. To overcome the lack of uniform cell distribution within a film a stratified sampling of the total film area is examined, which prevents the counting of any one area twice. The mean between-film coefficient of variation (S.D./x X 100) for all milk samples examined which contained more than 350,000 leucocytes/ml. was less than 10%.