Lung Air Cells.  — Each air cell varies in size from the seventieth to the one two-hundredth parts of an inch in diameter.  The number of aerosols in the two lungs is truly surprising, they’re been certainly not less than 600,000,000, though according to Dr. Addison’s computation there are 1,700,000,000, equivalent to 1,500 square feet [...]

Interior Arrangement of Lungs. — On turning this flap over we find a vertical section of lungs, showing their anterior arrangements. The lower end of the trachea divides, one portion going to each long. These again subdividing continue to subdivide in geometrical order, growing smaller and smaller with each division, and extending [...]