Its effect, when it reaches the circulation, is thus described by Dr.Richardson: "As it passes through the circulation of the lungs it is exposed to the air, and some little of it, raised into vapor by the natural heat, is thrown off in expiration.

If the quantity of it be large, this loss may be considerable, and the odor of the spirit may be detected in the expired breath.

If the quantity be small, the loss will be comparatively little, as the spirit will be held in solution by the water in the blood.

After it has passed through the lungs, and has been driven by the left heart over the arterial circuit, it passes into what is called the minute circulation, or the structural circulation of the organism.

The arteries here extend into very small vessels, which are called arterioles, and from these infinitely small vessels spring the equally minute radicals or roots of the veins, which are ultimately to become the great rivers bearing the blood back to the heart.