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22
for the presence of tubercle bacilli by animal experiment with
negative results.
Of the above 150 were examined by plate count to see if
they exceeded the limit of 100,000 per ml. prescribed by the
Milk (Special Designations) Order. Ninety-six samples were
below the limit whilst fifty-four were above.
Of 152 samples submitted to the Phosphatase test, 137
passed and 15 failed.
Those on which the Methylene Blue test was made numbered
148. 114 passed the test whilst 34 failed.
The large number of samples examined were occasioned by
trouble which occurred in respect of the milk from one firm.
Many complaints were received that the milk did not keep fresh
for a reasonable time after delivery.
I have found some difficulty in presenting figures which
correctly indicate the position and perhaps a few remarks on
this subject will prove informative.
I attach the greatest importance to the phosphatase test
which indicates whether or not milk has been properly pasteurised.
Correct pasteurisation reasonably ensures that all pathological
organisms have been eliminated. As can be seen 137
samples passed this test and 15 failed. On some occasions,
however, three samples were taken on the same day of the
milk from the same firm, at different points in the district. Often
these would represent the same bulk milk and two or three
failures (as did so happen) would really represent only one.
Similarly those that passed may represent fewer actual bulk
samples. The importance, however, is reflected in the failures
which might be reduced to half the number shown. I feel,
therefore, that so far as actual pasteurisation is concerned the
results are not unsatisfactory, as the percentage of failures would
be of reasonable proportions.