AUTONOMIC nerves, the vagal associated with groups of ganglion cells, enter the hilus of the lung and are distributed peripherally along the air passages. Fascicles of fibers and their subdivisions, derived from the nerves, distribute motor and sensory axons into the lung tissues, ultimately to their respective efferent terminals and afferent receptors.1,2 The efferent nonmyelinated postganglionic endings of the autonomic nerves are described3(pp 324-376) as a plexus of fibers and fibrils. The argyrophilic afferent receptors of the myelinated axons in the lungs are recorded1 as (1) fiber ramifications in the lining epithelium of bronchioles; (2) encapsulated or unencapsulated, sessile endorgans in the subepithelial tissues of the bronchioles and alveolar ducts, or pedunculated in the alveolar ducts and the alveolar sacs; (3) curved segments of thick sinuous fibers and their branches in the alveolar walls; and (4) plexuses of looped fibers in the bands of smooth muscle in