Clinicians have frequently observed that patients with a passive congestion in the lung due either to a heart condition, or resulting from a pulmonary condition, rarely develop clinical evidences of tuberculosis. A recent exposition of this view was put forward by Sewall,1 who described patients with labile vasomotor systems as well as with symptoms of neurasthenia. On physical and roentgen-ray examination, these patients reveal slight sclerosis of the hilum lymph nodes and upper bronchial radiations. These findings, Sewall asserts, are due to a "subtle intoxication" by the tubercle bacillus; they are nonprogressive, and most of the subjects of this toxemia never develop clinical tuberculosis.
Passive congestion in the lungs may result from a variety of clinical conditions. Very commonly, pulmonary irritation may occur in the form of bronchitis due to a degeneration in some part of the circulatory system. The lung vessels become engorged and the surface epithelial cells