effect of motion in the microscopic examination of blood. In the
blood, while it is circulating briskly in its vessels, there are
distributed through it, without contact with each other, the millions
of oxygen carriers called blood corpuscles. In the circulation in the
free channels of the body, the arteries and veins, it is motion that
keeps these corpuscles apart; we draw a drop of blood and let it come
to rest on the microscope glass, and as the motion ceases the
separated corpuscles run together, and adhere so firmly that we cannot
easily separate them without their disintegration. If we were able to
drive them in this state round the body, through the vessels, they
would not combine readily with the tissues; they have, in fact,
forfeited the condition necessary for such combination. So with the
oxygen they carry; when its invisible molecules are deprived of the
force called heat, which is motion, they do not readily combine with
new matter. But perfect combination of oxygen and carbon in the blood
is essential to every act of life. In the constant clash of molecule
of oxygen with molecule of carbon in the blood lies the mainspring of
all animal motion; the motion of the heart itself is secondary to
that. Destroy that union, however slightly, and the balance is lost,
and the animal body is, in a plain word, _ill_.

Cold or decreased temperature, below a given standard, which for sake
of comparison we may take at a mean of 40° Fahr., reduces this
combination of oxygen and carbon in blood. In my Lettsomian lectures
to the Medical Society of London, delivered in 1860, I entered very
fully into this subject, and illustrated points of it largely by
experiment. Since then I have done more, and although I have not time
here to state the details of these researches, I will epitomize the
principal facts. I found then that, by exposing blood in chambers into
which air can pass in and out, the blood could be oxidized at