of it than at present will have the hereditary
characteristics of the poorer classes and a much smaller part of it than
at present the hereditary characteristics of the well-to-do classes.

David Heron and others have recently studied[68] the relation which the
birth-rate in different boroughs of London bears to their social and
economic conditions. Using the correlation method, they found "that in
London the birth-rate per 1,000 married women, aged 15 to 54, is
highest where the conditions show the greatest poverty--namely, in
quarters where pawnbrokers abound, where unskilled labor is the
principal source of income, where consumption is most common and most
deadly, where pauperism is most rife, and, finally, where the greatest
proportion of the children born die in infancy. The correlation
coefficients show that the association of these evil conditions with the
relative number of children born is a very close one; and if the
question is put in another way, and the calculations are based on
measures of prosperity instead of on measures of poverty, a high degree
of correlation is found between prosperity and a low birth-rate.

"It must not be supposed that a high rate of infant mortality, which
almost invariably accompanies a high birth-rate, either in London or
elsewhere, goes far toward counteracting the effects of the differential
birth-rate. Where infant mortality is highest the average number of
children above the age of two for each married woman is highest also,
and although the chances of death at all ages are greater among the
inhabitants of the poorer quarters, their rate of natural increase
remains considerably higher than that of the inhabitants of the richer.

"From the detailed study of the figures made by Newsholme and Stevenson,
conclusions essentially the same as those of Heron can be drawn....
Their first step was to divide the London boroughs into six groups
according to the average number of domestic servants for 100 families in
each. This is probably as good a measure of prosperity as any other.
They then determined the total birth-rate of the population in each
group, and arrived at the following figures:

_Group_

I. 10 domestic servants for 100 families 34.97
II. 10-20 38.32
III. 20-30 25.99
IV. 30-40 25.83
V. 40-60 25.11
VI. Over 60