130 O. LARSELL 
SUMMARY 
1. Sensory nerve terminations are present in the epithelium 
of the primary bronchi within the lung and at the peints of 
division of the succeeding orders of bronchi. The most distal 
points at which they have been observed are in the walls of the 
atria of the lung. 
Differences in structure, correlated with position, suggest three 
functional types of sensory terminations. 
2. Nerve endings, probably motor and inhibitory, are present 
in the smooth muscle fibers of the bronchial musculature. 
3. The ganglionic cells of the intrapulmonary ganglia are 
surrounded by intracapsular, pericellular networks which are 
the terminal processes of nerve fibers, apparently of vagus origin. 
These cells give off axones which are distributed to the smooth 
muscle of the bronchial tree. There is a typical preganglionic 
and postganglionic fiber arrangement. 
4. The pulmonary artery and its branches, including the arte- 
rioles, havea rich innervation of fibers which terminate in relation 
to the smooth muscle cells of the tunica media. 
A few nerve fibers are also present in the walls of the pulmonary 
veins. 
