characters could not be transformed into
first-stage characters. He discusses this difficult question at some
length in the _Kampf der Theile_, coming to the conclusion that such
transmission takes place in small degree and gradually, and that many
generations are required before a new character can become hereditary.
He thinks that acquired characters are probably transmitted at the
chemical level. It is conceivable that acquired form-changes are
dependent on chemical changes, or are correlative with such, and that,
since the germ-cells stand in close metabolic relations with the soma,
these chemical changes may soak through to the germ-cells and so modify
them that a predisposition will appear in the descendants towards
similar form-changes.[485] From this point of view the problem of
transmission might be merged in the broader problem of the production of
form through chemical processes--the central problem of all development.

Inherited characters develop by an automatic process of
self-differentiation, and the separate parts of the embryo show during
this first period a surprising functional independence of one another.
But this state of things changes progressively as the second period is
reached, until finally all form-production and maintenance and all
correlation depend upon functioning. It is in the first period of
automatic development through internal "determining" factors that the
"developmental" functions in the strict sense, _e.g._ automatic growth,
division and self-differentiation, are most clearly shown. In the second
or "functional" period the formative influence of function upon
structure comes into play, and development becomes largely a matter of
"functional adaptation" to functional requirements.

All structure, according to Roux, is either functional or
non-functional. The former includes all structure that is adapted to
subserve some function. "Such 'functional structures' are, for example,
the composition of striated muscle fibres out of fibrillae and these out
of muscle-prisms, or again the length and thickness of the muscles, the
static structure of the bones, the composition of the stomach and the
blood-vessels out of longitudinal and circular fibres, the external
shape of the vertebral centra and of the cuneiform bones of the foot"
(p. 73, 1910). Indeed, as Cuvier had already pointed out, practically
every organ in the body shows a functional structure which is accurately
and minutely adj