. Annual report of the Commissioner of Agriculture ... Agriculture -- New York (State). New York Agricultural Experiment Station. 109 tains very few bacteria and the precise count makes little difference. If there are many bacteria present in the smear it is often impossible to count the whole field of the microscope, owing to confusion caused by lack of guide lines. An eye-piece micrometer, ruled in squares, overcomes this difficulty. Here, too, it is not necessary to count a large number of fields, for it is soon seen that the milk is of poor quality. Uneven distribution.— A more real source
. Annual report of the Commissioner of Agriculture ... Agriculture -- New York (State). New York Agricultural Experiment Station. 109 tains very few bacteria and the precise count makes little difference. If there are many bacteria present in the smear it is often impossible to count the whole field of the microscope, owing to confusion caused by lack of guide lines. An eye-piece micrometer, ruled in squares, overcomes this difficulty. Here, too, it is not necessary to count a large number of fields, for it is soon seen that the milk is of poor quality. Uneven distribution.— A more real source of error than the agree- ment or lack of agreement between duplicate counts is the uneven distribution of bacteria in the smear. It is evident that for accu-. Benton Hand Tally Register. rate quantitative work several fields must be counted to overcome this error. This is a laborious operation if large numbers of bac- teria are present. Fortunately practical experience has shown that accurate counts are not necessary in order to form a satisfactory idea of the amount of bacterial growth which has taken place in a given sample of milk. Counting is much more easily done if a hand tally register is used. This can be procured from hardware dealers. Counting of the whole field.— Another error which becomes important in some cases lies in attempting to count the whole microscopic field. The margin of the microscopic field is invariably so hazy as to obscure the bacteria lying in this region. This error is not serious, however, where few organisms are present, but becomes. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original New York (State). Dept. of Agriculture; New York State Agricultural Experiment Station; Cornell University. Agricultural Experiment Station. Albany : State of New York, Dept. of Agriculture
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