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test for the new grades of "tuberculin tested" and "accredited"
milk was not replaced by the methylene blue reduction test until
ist June, 1937. This new test replaces the plate-count method,
and is now the main bacteriological test used; but in addition it
is permissible to apply the test for the presence of coliform
organisms, the standard being that these grades of milk should
not contain such organisms in one-hundredth of a millilitre. The
Memorandum 139/Foods, January, 1937, states that it is not
necessary for both tests to be performed on every sample.
"Tuberculin Tested" milk. The number of samples which
were submitted to the methylene blue reduction test was 14. Of
these 13 were satisfactory and one failed to pass the test. The
time taken to decolorize in the sample which failed to pass was two
and a half hours. These samples were also submitted to the test
for coliform organisms. Of these, 12 passed the test and 2 failed,
one of which also failed to pass the methylene blue test. Of the
samples which failed to satisfy the test, coliform bacilli were

present in one hundredth of a millilitre in three tubes in one
sample and in two tubes in the other.
"Tuberculin Tested (Certified)" milk. Thenumberof samples
which were submitted to the methylene blue reduction test was 25.
Of these 23 were satisfactory and two failed to pass the test. The
time taken to decolorize in the samples which failed was four hours.
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