ems I strongly recommend to your attention.

This single illustration covers a wider ground than the special function
to which it belongs. We are learning that the chemistry of the body must
be studied, not simply by its ingesta and egesta, but that there is a
long intermediate series of changes which must be investigated in their
own light, under their own special conditions. The expression "sum of
vital unities" applies to the chemical actions, as well as to other
actions localized in special parts; and when the distinguished chemists
whom I have just cited entitle their work a treatise on the immediate
principles of the body, they only indicate the nature of that
profound and subtile analysis which must take the place of all hasty
generalizations founded on a comparison of the food with residual
products.

I will only call your attention to the fact, that the exceptional
phenomenon of the laboratory is the prevailing law of the organism.
Nutrition itself is but one great catalytic process. As the blood
travels its rounds, each part selects its appropriate element and
transforms it to its own likeness. Whether the appropriating agent
be cell or nucleus, or a structureless solid like the intercellular
substance of cartilage, the fact of its presence determines the
separation of its proper constituents from the circulating fluid, so
that even when we are wounded bone is replaced by bone, skin by skin,
and nerve by nerve.

It is hardly without a smile that we resuscitate the old question of
the 'vis insita' of the muscular fibre, so famous in the discussions of
Haller and his contemporaries. Speaking generally, I think we may say
that Haller's doctrine is the one now commonly received; namely, that
the muscles contract in virtue of their own inherent endowments. It
is true that Kolliker says no perfectly decisive fact has been brought
forward to prove that the striated muscles contract without having been
acted on by nerves. Yet Mr. Bowman's observations on the contraction
of isolated fibres appear decisive enough (unless we consider them
invalidated by Dr. Lionel Beale's recent researches), tending to show
that each elementary fibre is supplied with nerves; and as to the
smooth muscular fibres, we have Virchow's statement respecting the
contractility of those of the umbilical cord, where there is not a trace
of any nerves.

In the investigation of the nervous system, anatomy and physiology have
gone hand in hand. I