Section of the Lung of a Bird
In birds the lungs are confined to the back wall of the chest. They are not separated into lobes, but are oblong and flattened in shape, and connected with a series of air-receptacles scattered through various parts of the body. Shown is a section of a bird lung, magnified. Labels: 1, A bronchial tube that ends in a sac (caeca). 2, Division of the bronchial tubes that branch out among lobules. B, A plexus of capillary vessels.
Cutter, Calvin First Book on Analytic Anatomy, Physiology and Hygiene, Human and Comparative (Philadelphia: J. B. Lippincott & Co., 1875) 98