CHRONIC INTERSTITIAL PNEUMONIA. 201 



datory dilatation. In such a case, if the resisting power of the bron- 

 chial wall be less than that of the pulmonary substance, or if an ob- 

 struction in the smaller bronchi, or other impediment, hinder proper 

 expansion of the vesicles, it would seem that compensatory bronchi- 

 ectasis may arise in place of pulmonary emphysema. 



Finally, it is possible that some bronchiectases may be the result 

 of dilatation of the bronchial wall at points in the upper lobes of the 

 lung, where the tubes yield before the centripetal rush of air driver 

 into them from the alveoli by the act of coughing, and, while giving 

 way before the pressure, cause bronchiectasis instead of emphy- 

 sema. 



ANATOMICAL APPEARANCES. We rarely have the opportunity of 

 examining interstitial pneumonia before it begins to contract. We 

 then find the pulmonary substance solidified and void of air, in conse- 

 quence of swelling of the vesicular walls and scanty intervesicular and 

 interlobular connective tissue. At first it is hyperasniic and reddened ; 

 afterward of a paler, bluish-gray color. In several cases in which 

 bronchiectatic cavities have been found at the base of the lung in the 

 midst of indurated tissue, I have had an opportunity of observing ex- 

 tensive tracts of pale-red homogeneous substance, composed of young 

 connective tissue, and situated between portions of the lung which 

 contained air. 



Products of a later stage of the disease are much more frequently 

 met with. They consist of bands, or irregularly-shaped masses en- 

 twined in the pulmonary substance, are of a whitish color, or else are 

 blackened by pigment, and of a dense structure which " cries " under 

 the knife. They surround old masses of tubercle, which have already 

 become caseous, and tuberculous cavities, abscesses of long standing, 

 and the residue of the latter sometimes found in the lung in the shape 

 of calcified concretions. When croupous pneumonia terminates in in- 

 duration, entire lobes of a lung may become converted into this black- 

 ish, callous substance. 



In the autopsy of individuals who have worked in coal-mines, or 

 viio have inhaled coal-dust in other occupations, the lungs and bron- 

 chial glands are often found to be of a deeply-black hue. From the 

 results of recent investigation, there is no doubt that this coloration 

 depends upon the penetration into the lung of particles of coal. As a 

 rule, the pulmonary tissues sustain this intrusion of coal-dust remark- 

 ably well, and there are cases in which this anthracosis (that is, black- 

 ness resulting from deposit of coal-dust) has been the only lesion 

 found in the lung. In other cases, the black discoloration is combined 

 with an interstitial pneumonia, originating from the bronchial walls, 

 but often extending widely. In other instances, again, cavities are 



