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marked than the decline shown by the table in p. ooo in the
death-rate at all ages, there has been amongst the population over
ten years of age a far less marked decline or, at certain of the
higher ages, an actual increase in the death-rate. We shall have
presently (pp. ooo-ooo) to discuss fully this question of the
altered age incidence of fatal Small-Pox, both in England and
Wales and in Scotland and Ireland.
We have dealt so far with the evidence afforded by the
statistics of the mortality from small-pox at different epochs in
view of the spread or continued practice of vaccination. It seems
to us scarcely possible to deny that, speaking generally of the
British Isles, a more vaccinated population has exhibited a
diminished mortality from small-pox. It was not, of course, to
be expected that this should be seen year by year, or that the
correspondence should be exact, even assuming vaccination to be
the principal cause of this diminished mortality. We have
already pointed out that small-pox tends at times to become
epidemic, i.e., to spread more readily than at other times. The
occurrence of the conditions, whatever they may be, which cause
the disease to be thus epidemic have, of course, no relation to the
state of the population as regards vaccination, even conceding to
the full that it has a protective effect. The only result of widespread
vaccination, in a case where small-pox became epidemic,
could be to render the extent of the epidemic more limited, and
its fatality less than it would otherwise be. All that we should
anticipate then would be a general correspondence over a long
series of years between a vaccinated condition of the people and a
diminished mortality from small-pox.
In considering whether vaccination has been the principal
cause of the decline, we must inquire whether the other causes
suggested by those who deny the efficacy of vaccination will
satisfactorily account for it.
It is said that the decline has, in the main, been due to
changes in the general conditions of life in the different parts of