ic forms, but it is equally true
of them also." ... "It is not conceivable that the microscope should reveal
peculiarities of structure corresponding to peculiarities of habitual
tendency in the embryo, which at its first formation has no structure
whatever;"[199] and he adds that "there is something quite inscrutable and
mysterious" in the formation of a new individual from the germinal {186}
matter of the embryo. In another place[200] he says: "We know that in
crystals, notwithstanding the variability of form within the limits of the
same species, there are definite and very peculiar formative laws, which
cannot possibly depend on anything like organic functions, because crystals
have no such functions; and it ought not to surprise us if there are
similar formative or morphological laws among organisms, which, like the
formative laws of crystallization, cannot be referred to any relation of
form or structure to function. Especially, I think, is this true of the
lowest organisms, many of which show great beauty of form, of a kind that
appears to be altogether due to symmetry of growth; as the beautiful
star-like rayed forms of the _acanthometrae_, which are low animal organisms
not very different from the Foraminifera." Their "definiteness of form does
not appear to be accompanied by any corresponding differentiation of
function between different parts; and, so far as I can see, the beautiful
regularity and symmetry of their radiated forms are altogether due to
unknown laws of symmetry of growth, just like the equally beautiful and
somewhat similar forms of the compound six-rayed, star-shaped crystals of
snow."

Altogether, then, it appears that each organism has an innate tendency to
develop in a symmetrical manner, and that this tendency is controlled and
subordinated by the action of external conditions, and not that this
symmetry is superinduced only _ab externo_. In fact, that each organism has
its own internal and special laws of growth and development.

If, then, it is still necessary to conceive an internal law or "substantial
form," moulding each organic being,[201] and directing its development{187}
as a crystal is built up, only in an indefinitely more complex manner, it
is congruous to imagine the existence of some internal law accounting at
the same time for specific divergence as well as for specific identity.

A principle regulating the successive evolution of different organic forms
is not one whit