This is a black and white microscopic image of a section of a human lung. The image is labeled 'FIG. 50. SECTION OF HUMAN LUNG. x 20.' The central focus is a circular structure, likely an airway or bronchiole, filled with a bright white space. Surrounding this central structure is a complex network of lung tissue. This tissue appears as a dense, irregular pattern of cells and fibers. Several small, dark, circular or oval structures, likely blood vessels, are embedded within the tissue, surrounding the central airway. The tissue is highly textured and appears to be a cross-section, revealing the intricate internal structure of the lung. The image is a detailed anatomical illustration, showcasing the microscopic features of lung tissue.