THE DUNHAM FAN IN ROENTGENOGRAMS 
By First Lieut. PAuL S. SEABOLD 
Medical Corps, United States Army 
Without doubt, the factor most necessary in making a roent- 
genological diagnosis of pulmonary tuberculosis is a thorough 
knowledge of the finer anatomy of the lung. According to the 
most recent work of Dunham, of Cincinnati, we find that tuber- 
culosis, from both an etiological and a pathological standpoint, 
is more fully explained. 
Taking up the bronchial tree and going immediately to its 
most distal divisions, the respiratory bronchi, we find connected 
with these are many small alveoli known as the alveolar duc- 
tules, which in turn are again connected with the irregular atria. 
Emptying into the atria are the alveolar saccules, on all parts 
of whose circumference are found the pulmonary alveoli. The 
last division of the bronchial tree, before breaking up into the 
parenchymatous tissue of the lung, is the alveolar ductule; we 
consider it and all the air passages connected with it to be the 
primary lobule of the lung, the combination of great numbers 
of these making up the secondary lobule of the lung, which in 
turn makes up the bulk of the lung. 
The blood vessels to be considered are the pulmonary and the 
bronchial. 
The bronchial artery gives off its branches to the bronchi, 
connective and lymphoid tissues, also supplying the lymphatic 
glands at the hilum. This artery extends to the pleura by way 
of the thick connective tissue, giving blood supply there to the 
walls of the lymphatics. 
- The pulmonary artery follows the bronchial tree to its finest 
divisions, finally dividing into as many branches as there are 
atria. 
The bronchial veins are only found at the hilum where they 
empty into the vena azygos, while the pulmonary vein starts 
from the fine venules in the pleura and at the distal end of the 
alveolar ductules from the mesh of the pulmonary capillaries. 
The lymphatics form as a thick mesh in the walls of the 
bronchi which communicate freely with those of the pulmonary 
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