COLLAPSE OF THE LUNG. 131 



Alter state, which is normal during foetal life, may persist in portions of 

 the lung after birth. It is then called congenital atelectasis. In other 

 cases the air is absorbed, at a later period, from a number of the vesicles, 

 which then collapse. This is called acquired atelectasis, or collapse of 

 the lung. In other instances the air is expelled from the vesicles by 

 external pressure. We then speak of compression of the lung. Con- 

 genital atelectasis is most frequently found in feeble children, particu- 

 larly those who have been born prematurely, or who have come into the 

 world in a state of apparent death after tedious labor. It would seem 

 as though air-vesicles, which do not become filled with air immediately 

 after birth, are subsequently more difficult of inflation, so that children, 

 which are not induced to cry, and thereby caused to make deep inspi- 

 rations during the first hours of their life, very commonly suffer from 

 atelectasis. In other instances a catarrh, either congenital or contracted 

 in the first hours of life, seems to have given rise to atelectasis by con- 

 tracting or occluding some of the bronchi, and thus impeding the sup- 

 ply of air to the vesicles to which they lead. Collapse of the lung, or 

 acquired atelectasis, is always connected with acute or chronic bronchial 

 catarrh, and is of somewhat frequent occurrence in children, as their 

 bronchi are small and easily obstructed. In adults it is a peculiarly fre- 

 quent complication of the catarrh, which is one of the symptoms of 

 typhus (typhoid?). Compression of the lung takes place in conse- 

 quence of the presence of liquid or air, more rarely of a tumor in the 

 pleural sac, from effusions in the pericardium, from aneurisms, curvature 

 of the spine, arrested development of the thorax, and finally, from volu- 

 minous effusions in the abdominal cavity, by which the diaphragm is 

 driven upward. 



ANATOMICAL APPEAKANCES. In congenital atelectasis circum- 

 scribed spots in the parenchyma, more rarely the half or the whole 

 lobe of a lung, are found to be depressed somewhat below the level of 

 the surrounding parts. These spots are of a dark-blue color, firm, do 

 not crackle, and, when cut into, present to view a smooth surface 

 abounding in blood. At first they may be readily inflated, afterward 

 they become more rigid, contain less blood, and it is no longer always 

 possible to inflate them. The areolar walls seem to be fast glued or 

 grown together. The alterations of the parenchyma in acquired atelec- 

 tasis are essentially the same as those just described. Rokitansky for- 

 merly called it catarrhal pneumonia. The blue, depressed spots here 

 contrast more against the surrounding emphysematous lung. If we 

 cut into the atelectatic spot, we usually come upon a thick, muco-puru- 

 lent plug, which has stopped up the bronchus leading to it. When the 

 atelectasis is of long standing, other changes take place in the collapsed 

 portion of the lung, which belong to that very frequent sequel of this 



