nto and absorbed by the glands of the womb, and he discusses the
probability that such absorption profoundly and beneficially affects
the physiological reaction in the woman. He points out that the use of
artificial checks "while preventing fertilisation may also be the
means of depriving the female of certain secretions which may exercise
a far reaching influence on her economy"; and he concludes, "As a rule
we cannot interfere with the normal course of nature without some
consequent evil result. May this not be an instance in which for some
apparent gain in one direction, the woman pays the penalty?"

CHAPTER IV

THE EFFECT OF WIDESPREAD CONCEPTION CONTROL ON NATIONAL EFFICIENCY

In every nation individual capacity varies within wide limits. We have
men and women of brilliant attainments, and of all grades of
intelligence ranging downwards to the mentally defective. There is no
doubt that all grades of intelligence can be improved by education,
but there appears to be a limit to the capacity of development of each
individual. Lower intelligence, therefore, is not only due to lack of
opportunity, but to an inborn constitutional defect.

Further study has shewn this defect to be hereditary--the parents or
grandparents of such people shew defective intelligence, and their
offspring are likely to do the same; indeed, if two mentally defective
people marry it is fairly certain that their children will all be
mentally defective.

There are, however, no sharply defined classes of intelligence; just
as the mentally defective are in many grades, so ordinary men and
women vary from low or average intelligence up to outstanding cases of
genius or capacity.

By the newer methods of mental testing it has been shewn that children
of various classes of the community, as well as men and women of
different races, can be grouped according to their intellectual
capacity, and that no educational facilities will develop that
capacity beyond a certain point.

Professor W. McDougall, F.R.S., in his most useful and interesting
book on _National Welfare and National Decay_, reaches the important
conclusion "that innate capacity for intellectual growth is the
predominant factor in determining the distribution of intelligence in
adults, and that the amount and kind of education is a factor of
subordinate importance." He claims that the evidence is overwhelming
as to the validity of the results obtained by mental testing.

A fe