because they touch and revive the deep basic emotions of the race. Thus we see
that play is not doing things to be useful later, but it is rehearsing racial history.
Plays and games change only in their external form, but the underlying neuro-
muscular activities, and also the psychic content of them, are the same. Just as
psychic states must be lived out up through the grades, so the physical activities
most be played off, each in its own time.
The best exercise for the young should thus be more directed to develop the
basal powers old to the race than those peculiar to the individual, and it should
enforce those psycho-neural and muscular forms which race habit has banded
down rather than insist upon those arbitrarily designed to develop our ideas of
symmetry regardless of heredity. The best guide to the former is interest, zest,
and spontaneity. Hereditary moment, really determine, too, the order in which
nerve centers come into function. The oldest, racial parts come first, and those
which are higher and represent volition come in much later.[2] As Hughlings
Jackson has well shown, speech uses most of the same organs as does eating, but
those concerned with the former are controlled from a higher level of nerve-
cells. By right mastication, deglutition, etc., we are thus developing speech
organs. Thus not only the kind but the time of forms and degrees of exercise is
best prescribed by heredity. All growth is more or less rhythmic. There are
seasons of rapid increment followed by rest and then perhaps succeeded by a
period of augmentation, and this may occur several times. Roberts's fifth
parliamentary report shows that systematic gymnastics, which, if applied at the
right age, produce such immediate and often surprising development of lung
capacity, utterly fail with boys of twelve, because this nascent period has not yet
come. Donaldson showed that if the eyelid of a young kitten be forced open
prematurely at birth and stimulated with light, medullation was premature and
imperfect; so, too, if proper exercise is deferred too long, we know that little
result is achieved. The sequence in which the maturation of levels, nerve areas,
and bundles of fibers develop may be, as Flechsig thinks, causal; or, according to
Cajal, energy, originally employed in growth by cell division, later passes to
fiber extension and the development of latent cells; or as in young children, the
nascent period of finger movements may stimulate that of the thumb which
comes later, and the independent movement of the two eyes, their subsequent
coördination, and so on to perhaps a third and yet higher level. Thus exercise
ought to develop nature's first intention and fulfil the law of nascent periods, or
else not only no good but great harm may be done. Hence every determination of
these periods is of great practical as well as scientific importance. The following
are the chief attempts yet made to fix them, which show the significance of