The carrier cells—the red-corpuscles of the blood—travel in the arteries and veins, carrying a load of oxygen on the outward arterial trip, and bringing back a return cargo of the waste products of the system to be burned up in the lungs. Other cells force their way through the walls of the arteries and veins, and through the tissues of the body, on repair work. The police cells, and the soldier-cells, in the blood protect the system from the attacks of germs, bacteria, and other harmful visitors or invaders. One of the protecting cells coming in contact with an intruder of this kind will enmesh it, and then proceed to devour it; if the task be too heavy for one cell it will call the assistance of others, and the combined force will seize the intruder and try to eject it from the system.

Timaeus: and lays hold on the meats and drinks, it dissolves them, and dividing them into small particles it disperses them through the outlets by...

Timaeus: any nourishment to the body; for they move through the veins in all directions and no longer preserve the order of their natural...