ng of physical forces in physiological processes. Wherever
rigid experiment carries us, we are safe in following this lead; but the
moment we begin to theorize beyond our strict observation, we are in
danger of falling into those mechanical follies which true science has
long outgrown.

Recognizing the fact, then, that we have learned nothing but the
machinery of life, and are no nearer to its essence, what is it that we
have gained by this great discovery of the cell formation and function?

It would have been reward enough to learn the method Nature pursues for
its own sake. If the sovereign Artificer lets us into his own
laboratories and workshops, we need not ask more than the privilege of
looking on at his work. We do not know where we now stand in the
hierarchy of created intelligences. We were made a little lower than the
angels. I speak it not irreverently; as the lower animals surpass man in
some of their attributes, so it may be that not every angel's eye can see
as broadly and as deeply into the material works of God as man himself,
looking at the firmament through an equatorial of fifteen inches'
aperture, and searching into the tissues with a twelfth of an inch
objective.

But there are other positive gains of a more practical character. Thus we
are no longer permitted to place the seat of the living actions in the
extreme vessels, which are only the carriers from which each part takes
what it wants by the divine right of the omnipotent nucleated cell. The
organism has become, in the words already borrowed from Virchow, "a sum
of vital unities." The strictum and laxum, the increased and diminished
action of the vessels, out of which medical theories and methods of
treatment have grown up, have yielded to the doctrine of local
cell-communities, belonging to this or that vascular district, from which
they help themselves, as contractors are wont to do from the national
treasury.

I cannot promise to do more than to select a few of the points of contact
between our ignorance and our knowledge which present particular interest
in the existing state of our physiological acquisitions. Some of them
involve the microscopic discoveries of which I have been speaking, some
belong to the domain of chemistry, and some have relations with other
departments of physical science.

If we should begin with the digestive function, we should find that the
long-agitated question of the nature of the acid of the gastric juic