CHAPTER L. 



SrOEADIC DISEASES— continued. 



LOCAL DISEASES— co?ifwMaZ. 



(/.) DISEASES OF THE EESPIEATOEY Q-RGANS— continued. 



CHEOI^IC EMPHYSEMA OF THE LUNGS. 



Chronic Emphysema of the lungs is of two kinds, namely — (1.) 

 Vesicular, due to enlargement and dilatation of the air cells, with 

 gradual effacement of the blood-vessels distributed over their 

 walls. There is anaemia of the affected parts, a tendency to dila- 

 tation of the right cardiac ventricle, and a disposition to anasarca 

 of the limbs. The dilated cells vary in size, and when very 

 large it is probable that several vesicles are dilated into one 

 cavity by rupture of the vesicular walls and partitions. These 

 dilatations may be clearly seen through the pulmonary pleura, 

 as they protrude from the surface of the lungs ; they are pale, 

 sometimes quite white, the tissue drier than natural. Vesicular 

 emphysema is seen in chronic broken wind, and is due, as 

 already explained, to degeneration of the bronchial tissues. It 

 is, however, a result of bronchitis, and several theories are put 

 forward to explain the origin of emphysema. Dr. ElHotson 

 considers that a want of due expansion of the lungs is the most 

 common cause. He says — " Whatever prevents any one part of 

 the lungs from expanding when the thorax expands, whether it 

 be a material obstruction of the bronchial ramifications or a 

 compression of them, or whatever else, it will occasion those 

 parts which remain dilatable to keep dilated in a corresponding 

 increased degree, in order to fill up the vacuum which the ex- 

 pansion of the chest occasions. When we inspire we dilate the 

 chest, and the air rushes down the trachea, and the lungs follow 



