94 Clin.iiir Alvc.ilar Bloatiii- 



If tliis process s'0^« oii iii the lungs it leads to a successive 

 decrease of elasticity, hence the lungs will increase their size 

 with difficulty during respiration and also decrease it with 

 difficulty in expiration, so that a gradual increase in the volume 

 of the lungs is produced. The obliteration of a portion of the 

 pulmonary capillaries which bring about the exchange of gases, 

 leads to a decrease of the respiratory surface, to an increase 

 in pressure in the pulmonary artery and consequently to a 

 hypertrophy of the walls of the right side of the heart. The 

 decrease of elasticity and the diminution of the respiratory 

 surface cause dyspnea which is particularly manifest in ex- 

 piration. Deficient ventilation of the air passages, and changes 

 in the lesser blood circulation predispose the animals to 

 bronchial catarrh. 



Anatomical Changes. The lungs appear larger, softer and 

 less ehistic (more like an air-cushion) and in consequence of 

 the diminished blood-supply also paler than normal; their 

 surfaces frequently show the impressions of the ribs (this is 

 important from a forensic standpoint). The changes are most 

 marked toward the inferior and posterior borders. The 

 diaphragm appears raised posteriorly, the heart is covered by 

 the lungs to an increased extent. The margins of the lungs 

 are rounded off, individual air vesicles can be recognized with 

 the naked eye and between them sometimes larger air spaces, 

 up to the size of a hazelnut. If cut into, the lung tissue col- 

 lapses more slowly than under normal conditions and without 

 crepitation ; the cut surface is pale red and discharges only 

 a small amount of foamy blood; small droplets of pus, which 

 appear on pressure, point to the existence of bronchial catarrh. 

 The enlarged lungs are lighter in weight than those of healthy 

 animals. 



Stommer has investigated the histologic changes and has ascertained that 

 the diameter of the alveoli is increased from a normal of 0.15 mm. to 1.5 mm., 

 while the diameter of the interalveolar septa is decreased from 8 fi to 1-2 /x. The 

 vessels ai'e more straight, their Inmen is narrowed, partially obliterated. The number 

 of elastic fibers is decreased, the alveolar epithelia are in a state of fatty degenera- 

 tion. Rindfleisch found in the lungs of man that new vessels are formed partially 

 in place of those that have become obliterated; this change is brought about by 

 a new-formation from branches of the pulmonary artery which enter into anastomosis 

 with branches from the bronchial artery. The involuntary muscle fibers of the 

 bronchial wall are increased. 



Hypertrophy of the right cardiac ventricle is found in 

 advanced cases, in the most severe cases also dilatation with 

 symptoms of general congestion. 



Tn senile atrophy of the lungs (atrophia senilis pulm.) the ])icture is similar, 

 because the alveoli have become enlarged secondarily, ex vacuo, in consequence of 

 tissue atrojihy. Such lungs are, however, never enlarged. They ai'e, on the contrary, 

 smaller ami there is no hj^^iertrophy of the right side of the heart. 



Symptoms. A¥ith the usual methods no changes can be 

 demonstrated in the lungs while the disease is in its stage 



