The circulation of the blood maintains health, and consequently life by carrying away from the various parts of the body the particles of worn-out and poisonous tissue, and replacing them with fresh, structure-building material.
b.

The man is healthiest in whom this process goes on most freely and continuously.
c.

Men of considerable muscular power are disposed to be sluggish; the exertion of great strength does not favor circulation.

It rather retards it, and disturbs its equilibrium by congesting the blood in quantities in the sets of muscles called into action.
d.

In light, active men, on the other hand, the circulation goes on perfectly and evenly, because all the parts are put in motion, and kept so in such a manner as to promote the movement of the blood to every extremity.