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27
Bacteriological Examination of Milk.
Twenty-five samples of milk were examined for the presence of tubercle
bacilli. One sample only disclosed evidence of tuberculous infection. In this case
post-mortem examination of two guinea pigs, killed at the end of three and six
weeks respectively after inoculation, showed enlarged and nodular spleens: the
second animal also showed abscess at the site of inoculation in which tubercle
bacilli were noted microscopically. This milk was not sold as " pasteurised "
but was in fact a milk pasteuried under the Holder method. The milk
came to a London distributing depot from a receiving station in the North of
England where the supply is derived from a thousand farms. At the receiving
depot the milk is mixed and brine cooled before transport in insulated rail tanks
to London where it is pasteurised. Communications on the subject were sent to
the retail vendor, the wholesalers, and to the Medical Officers of Health of the
districts where the milk is mixed and where it is subsequently pasteurised.

Designated Milk.
Four samples of designated milks were submitted for bacteriological
examination for the presence of Brucella Abortus infections. The milks
examined were "Certified," "Grade A (T.T.)," "Grade A Pasteurised" and
" Pasteurised."
From the following report it will be seen that no sample gave evidence of
Brucella Abortus infection:—
Four series of guinea pigs were inoculated with deposits and cream
" from each of the milks respectively.
" The animals were killed at intervals after a period of three weeks.
" Samples of blood were collected from each, and agglutination tests
" carried out with Standard Br. Abortus cultures. Portions of spleen and
" liver of each were cultured and incubated under C02 conditions.
" Neither by agglutination or culture was any evidence obtained of the
" presence of Brucella Abortus infections."