This is a condition of tubercular infection that lacks many of the characteristics of chronic tuberculosis. Clinically considered it is nearly identical with interstitial pneumonia. There is an increased amount of fibroid tissue or of connective tissue elements in the diseased area, which condition may be observed when there is no tubercular development present. There is ultimate contraction of the lung substance, and thus a reduction in the size of the affected lung, which becomes hardened and dense. This disease is insidious and of very slow development. The general health of the patient is not materially impared at the first, and consequently the disease may be overlooked, until it is firmly established. While cough is present, the expectoration is not characteristic and the respiration is not essentially increased, although the breathing may be embarrassed, especially upon exertion. There is but little emaciation and only a very gradual loss of strength. These conditions appear during middle life and may continue a number of years. In the latter stages paroxysmal coughing is a permanent condition, the spells occurring usually on rising in the morning, with the greatest seventy, and in a milder form during the day. A severe paroxysm may occur also during the night. With these there is a purulent expectoration of an offensive sputum, which may be present in large quantities, with difficult breathing and now greatly impaired general health. As the disease has progressed, changes have taken place also in the heart, liver or kidneys, resulting in chronic disease of these organs, which may terminate in dropsy or other characteristic manifestation.