CHRONIC INTERSTITIAL PNEUMONIA. 199 



siderable harm by reducing the strength of the patient, lowering the 

 energy of the inspirations, and thus tending to encourage the spread 

 of pulmonary collapse ; and here I will again briefly call to mind the 

 value of emetics, transitory as it may be, and the frequent lack of suc- 

 cess in their use. It has been of great interest to me, that both 

 Bartels and Ziemssen strongly commend the application of cold com- 

 presses to the chest (proposed by me in croupous pneumonia), as by- 

 far the most efficient mode of treatment. 



CHAPTER XI. 



CHRONIC INTERSTITIAL PNEUMONIA INDURATION OF THE LUNG- 

 BRONCHIECTATIC CAVITIES. 



ETIOLOGY. The lung, when healthy, has but little connective tis- 

 sue in its composition. A portion of this combines with numerous 

 elastic fibres to form the pulmonary air-cells ; another portion serves 

 to bind together the lobules, while a third belongs to the walls of the 

 blood-vessels and bronchi. There is a large class of cases in which, 

 instead of these mere rudiments of connective tissue, we find large 

 sections of the lung converted into a callous, fibrous mass, the product 

 of a chronic interstitial pneumonia, which must be regarded as one of 

 the most frequent of diseases. 



In chronic pneumonia there is no free exudation either into the air- 

 cells, or their interstices, excepting in that form of the affection known 

 as caseous infiltration, of which we shall speak by-and-by, while treat- 

 ing of pulmonary consumption. While in croupous and catarrhal 

 pneumonia the pulmonary tissues themselves suffer little or no nutri- 

 tive disturbance, in the form, of inflammation at present under con- 

 sideration it is precisely this pulmonary intercellular and interlobular 

 connective tissue which is attacked. The process consists in a hyper- 

 plasia of the connective tissue, resulting in an augmentation of the 

 substance of the lung, and in a diminution of its cavities for the recep- 

 tion of air. The newly-formed material, by which the lung is solidified, 

 then undergoes further changes, as do all other neoplastic formations 

 of connective tissue arising from inflammation. At first soft and filled 

 with blood, it afterward contracts, and is transformed into a callous, 

 bloodless substance, occupying a smaller amount of space than was 

 formerly filled by the healthy lung. 



Chronic interstitial pneumonia scarcely ever occurs as an indepen- 

 dent and primary disease. Even in the interesting cases observed to 

 follow the inhalation of iron or coal-dust, the induration is not a direct 

 result of such inhalation of irritating substances, but only appears 



