hin the nervous system which accompany
stimulations and responses bring about changes in the structure of the
organism. The cause for these changes seems to be that the neurons which
chance to work together during any experience form connections with one
another by means of their outgrowing fibres. By this means, traces of
past experiences are in a sense stored up within the organism, and it is
for this reason that our experiences are said to be recorded within the
nervous system.

=B. Retentiveness.=--A second characteristic of nervous matter is its
retentive power. In other words, the modifications which accompany any
experience, besides taking on the permanent character referred to above,
pre-dispose the system to transmit impulses again through the same
centres. Moreover, with each repetition of the nervous activity, there
develops a still greater tendency for the movements to re-establish
themselves. This power possessed by nervous tissue to establish certain
modes of action carries with it also an increase in the ease and
accuracy with which the movements are performed. For example, the
impressions and impulses involved in the first attempts of the child to
control the clasping of an object, are performed with effort and in an
ineffective manner. The cause for this seems to be largely the absence
of proper connections between the centres involved, as referred to
above. This absence causes a certain resistance within the system to the
nervous movements. When, however, the various centres involved in the
movements establish the proper connections with one another, the act
will be performed in a much more effective and easy manner. From this
it is evident that the nervous system, as the result of former
experiences, always retains a certain potential, or power, to repeat the
act with greater ease, and thus improve conduct, or behaviour. This
property of nervous matter will hereafter be referred to as its power of
retention.

=C. Energy.=--Another quality of nervous matter is its energy. By this
is meant that the cells are endowed with a certain potential, or power,
which enables them to transmit impressions and impulses and overcome any
resistance offered. Different explanations are given as to the nature of
this energy, or force, with which nervous matter is endowed, but any
study of these theories is unnecessary here.

=D. Resistance.=--A fourth characteristic to be noted regarding nervous
matter is that a nervo