Part 2
As we have seen in the preceding blogpost, there was discussion about whether good
and bad streptococci are present in the milk, and , since they cannot be distinguished with methods
available in 1907, we have to accept two facts, Harris tells us (1):
First that
there exists in udders of normal cows a certain species of bacterium, in great
numbers, that performs its service to the dairyman; second that streptococci
are observed universally in milk. But Harris does not think that the latter
fact “is evidence that the cows giving the milk are diseased and that the milk
is in consequence unfit for the use of the human subject.” For if it were
evidence “then we would be bound to acknowledge that for the greater part milch
cows suffer more or less continuously from inflammation of the udder.”
Harris now
proceeds with a speculation (his word) based on a view of some colleagues that
the normal lactic acid bacteria of the udder are streptococci, which are for
the most part non-pathogeneic. The speculation is that he assumes “that after a
time the cocci gradually part with their pathogeneic powers, and, undergoing
some modification, give themselves over to a saprophytic existence, comparable
to that led by bacteria in the mouths and intestines of the human subject.”
Harris is
aware that his arguments for a more doubtful significance of streptocci in milk
may not be satisfying, but his aim is a careful reinvestigation of the facts,
to “arrive, it is to be hoped, at no distant day to a much clearer point of
view … regarding the status of the presence of streptococci in milk.”
There
remains a second important question in accordance with the title of the
publication, that is the presence of the so-callled “pus cells”, or leucocytes
in milk.
(to be
continued)
1.
N.M.Harris, ‘The relative importance of streptococci and leukocytes in milk’, The Journal of Infectious Diseases, 4
(1907) 50-62.
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