carded by English chemists, Dr. Black leading the way, and therefore
it did not then appear in English systems of chemistry. But from that
time, I cherished it with a mother's devotion, watched changes in my own
physical frame relating to it, taught it to my pupils, and held warm
disputes with the medical faculty, who opposed and contemned it.

In the summer of 1832, the Asiatic cholera appeared among us, appalling
every heart. This plague, I said, is a disease of coldness and
obstruction; and these doctors, wrong as they are on the subject of
animal heat, can never understand it--though, if Lavoisier were living,
he might. Let me, then, as best I may, consider anew the problem of heat
as produced by respiration, and see whether I cannot find out something
which has a bearing on the fatal coldness of this fearful disease. It is
into the lungs, and no where else, that breathing introduces atmospheric
air; and it is there that the oxidation of carbon or animal combustion
takes place. Thus must caloric be imparted to the blood in the lungs;
and in them is one-fifth of the blood of the system, of which
seven-eighths is water.

The nature of heat is to expand all fluids. The blood in the lungs must,
therefore, expand; and if it expands, it must move; and if it moves, it
must, from the organism of the parts, move to the left ventricle of the
heart, into which the valvular system opens to give it a free
passage--whereas the valves of the right close against it. "Eureka!" I
mentally exclaimed; "I have found the _primum mobile_ of the circulation
of the blood." I had for years disbelieved that the heart's slight
mechanical impulse was that cause. In teaching Paley's "Natural
Theology," my mind had come in contact with the passage in which he
describes the heart's more than Herculean labors; and I said, "This is
altogether too much--the heart alone cannot perform all this--there must
be some other power," and an abiding desire to know what that power
could be, prepared me for receiving this great idea. But my mind was
agitated by it, as the sea is, when a great rock is thrown into its
waters.

The cholera was then raging around me; and as I prepared to flee from it
to a mountain air, I confided to a scientific friend, Professor Twiss of
West Point, my hypothesis, which I regarded as probably the incipient
germ of an important discovery.

But there was first the former theory to be disproved; and then there
were new points to