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in old age. The first peak is due to respiratory tuberculosis of the
infantile type to some extent, but chiefly non-respiratory tuberculosis.
There is reason to believe that this peak is due to primary
infection. The last three peaks are entirely due to respiratory
tuberculosis.
The second peak occurs in the 20-25 age-period in females and
in the 25-30 age-period in males. This peak is well marked in
females and is now in fact the principal peak.
The third peak occurs in males in the 45-50 age-period, and
somewhat earlier in females. This is at present the peak of highest
mortality in males.
The fourth peak occurs in the 60-65 age-period in both sexes.
These peaks are not peculiar to the mortality graph of this
country. In some countries one peak predominates, in others,
another.
If the causation of these peaks was thoroughly understood, we
might possess information of the greatest value in directing our
efforts for the prevention of tuberculosis.
BOVINE TUBERCULOSIS
A certain proportion of human tuberculosis is caused by the
bovine tubercle bacillus, and Dr. A. Stanley Griffith, from the
work which he has done on this subject for the Medical Research
Council, estimates that at least 5% is due to this type of tubercle
bacillus.
During the past ten years there has been a marked fall in the
number of deaths from non-pulmonary tuberculosis. Part of the
improvement must be attributed to a safer milk supply. The
inspection of herds, farms, dairies and milk distributing centres,
the bacteriological testing of samples of milk for tubercle bacillus
and the increasing attention paid to the pasteurisation of milk, are
all measures which must materially contribute to this improvement
FAMILY INFECTION.
The influence of family infection has been shewn by an investigation
made in the County of Lancashire into the death-rate from
non-pulmonary tuberculosis in children under five years expose