H.—-ANTHROPOLOGY. 199 
the stenches of the cells, though the modern explanation would suggest that 
they might have acquired immunity from previous and possibly slight 
attacks. It has been argued that such epidemic diseases served a useful 
purpose in that they removed weaklings, but the type selected by this test 
of relative immunity to typhus or gaol fever is not one to be commended 
on account of its mental or physical traits. The general statement is 
however open to doubt; Ballard ** reporting on the Leicester outbreak 
of infantile diarrhcea in 1881 stated, ‘ Our experience of these epidemics 
by no means supports an opinion commonly held that a summer diarrhea 
makes its first fatal swoop upon the weakliest children.’ While the alleged 
benefits to the community of this mortality are neither uniform nor un- 
doubted, the evil effects of infectious disease are very real, for it is a matter 
of common observation that the effect of these illnesses, especially in 
children, is to lower the vitality and reduce the physique sometimes even 
permanently. 
In endeavouring to trace the changes in mortality in England it will 
be noted that in early days all is expressed in vague terms, e.g. that in the 
days of the Black Death ‘a fifth part of the men, women and children in 
all England were consigned to the grave’ ; * occasionally a local chronicle 
records of certain years that the burials greatly outnumbered the chris- 
tenings, but definite information only begins with the London bills of 
mortality in late Tudor times. From them we learn that in the liberties 
of the City, within and without the walls during the great plague years, 
the mortality ranged from 200 to over 400 per 1,000 living, and that in 
healthy years, which were few, the rate was some 60 per 1,000. The 
subsequent history of London is one of steady fall of mortality, though the 
greatest change has occurred in our own lifetime. In the latter part of 
the seventeenth century the rate was 80 per 1,000 living, in the eighteenth 
century it was 50, by the middle of the nineteenth century it was only 
25, and since 1875 it has fallen rapidly to the present rate of 11-12 per 1,000. 
Some part of this change is due to variations in the age and sex constitution 
of the population at risk, but even when all corrections for this have been 
made, the mortality rate in England and Wales has fallen over a third 
since the beginning of registration in 1838. 
A great part of this reduction has been in the infant mortality, which 
is perhaps the most important from the standpoint of potential parenthood. 
This mortality in early years was very high: thus in 1754 the deaths in 
London of children under two years of age were 45 per cent. of the deaths 
at all ages. Since the period of registration the infant mortality oscillated 
around 160 per 1,000 until 1900, since when it has fallen to 60 per 1,000 in 
1923. The great part of the fall has been in deaths due to infectious 
diseases and diarrhoea ; there has been little or no change in the rates 
from congenital defects or developmental disorders, which have remained 
relatively unchanged in all classes of the community, so that this lethal 
selection against the naturally unfit remains as rigid as ever. The fall 
in the mortality rate has been ascribed to various features: cleaner milk, 
fewer flies, the disappearance of the old feeding-bottle, and it seems to 
be most certainly connected with increased skill in maternal care. Thus 
4 Ballard, Report of Local Government Board, 1889, p. 43. 
*° Bulogium Histeriarum, Rolls ser., No. 9, IT!., 213. 
