er poor environmental influences, or
when a child of poor stock is reared under good influences, the results
seem to show that the differences in environment have little effect on
mental development, as far as the fundamental functions are concerned,
except in the most extreme cases.

Each mental function is capable of some development. It can be brought
up to the limit of its possibilities. But recent experiments indicate
that such development is not very great in the case of the elementary,
fundamental functions. Training, however, has a much greater effect on
complex mental activities that involve several functions. Rote memory is
rather simple; it cannot be much affected by training. The memory for
ideas is more complex; it can be considerably affected by training. The
original and fundamental functions of the mind depend upon the nature of
the nervous system which is bequeathed to us by heredity. This cannot be
much changed. However, training has considerable effect on the
cooerdinations and combinations of mental functions. Therefore, the more
complex the mental activities which we are testing, the more likely they
are to have been affected by differences in experience and training.

If we should designate the logical memory capacity of one person by 10,
and that of another by 15, by practice we might bring the first up to 15
and the second to 221/2, but we could not equalize them. We could never
make the memory of the one equal to that of the other. In an extreme
case, we might find one child whose experience had been such that his
logical memory was working up to the limit of its capacity, while the
other had had little practice in logical memory and was therefore far
below his real capacity. In such a case, a test would not show the
native difference, it would show only the present difference in
functioning capacity.

Fairly adequate tests for the most important mental functions have been
worked out. A series of group tests with directions and norms follow.
The members of the class can use these tests in studying the individual
differences in other people. The teacher will find other tests in the
author's _Examination of School Children_, and in Whipple's _Manual of
Mental and Physical Tests_.

=MENTAL TESTS=

GENERAL DIRECTIONS

The results of the mental tests in the school will be worse than useless
unless the tests are given with the greatest care and scientific
precision. Every test should be most