Note 1 — SECTION I.

It is here seen what an important work this theory does for the venous circulation, and why the blood moves into the lungs. We have read of a theory which maintains that it goes there because there is a mutual attraction between it and the capillaries of the lungs. But there is none between the water in our tube and that in the tin vessel where water is boiling; but it goes into it with a rush notwithstanding. Because there is a strong suction power produced by expansion, no other attraction is needed. The apparatus, as here described, goes no farther than to represent the circulation in single-hearted animals. But in my work is a drawing which shows the left heart on the opposite of the mimic lungs from the right; and then how the same tube, by being folded in the form of a figure eight (8), shows the two hearts united into one, and both ventricles working by the same contractions to perform their different tasks.