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From a section of the lung of a cat, stained with silver nitrate. Labels: A. D., alveolar duct or intercellular passage; S, alveolar septa; N, alveoli or air cells, lined with large flat, nucleated cells, with some smaller polyhedral nucleated cells; M, Unstriped muscular fibers. Circular muscular fibers are seem surrounding the interior of the alveolar duct, and at one part is seen a group of small polyhedral cells continued from the bronchus.

Air Cells from a Cat's Lung

From a section of the lung of a cat, stained with silver nitrate. Labels: A. D., alveolar duct or intercellular…

Terminal branch of a bronchial tube, with its infundibula and air cells from the margin of the lung of a monkey, injected with quicksilver. Labels: a, terminal bronchial twig; b, infundibula and air cells.

Air Cells of a Monkey

Terminal branch of a bronchial tube, with its infundibula and air cells from the margin of the lung…

Two small infundibula or groups of air cells, a, with air cells, b, and the ultimate bronchial tubes, c, with which the air cells communicates. From a newborn child.

Infundibula

Two small infundibula or groups of air cells, a, with air cells, b, and the ultimate bronchial tubes,…