ATROPHY OF THE LUNG. 109 



CHAPTER II. 



ATROPHY OF THE LUNG. EMPHYSEMA SENILE. 



BY atrophy of the lung we mean that attenuation, thinning, and 

 gradual wasting of the vesicular walls, which results from imperfect 

 nutrition of the lung. We most commonly see this wasting of the pul- 

 monary tissue in old age, when it is accompanied by atrophy of other 

 organs, and by general marasmus. Sometimes the atrophy of the lung 

 occurs sooner and more completely than involution of the rest of the 

 body, and in these cases the symptoms are more decided. Through 

 wasting of their septa, several, and sometimes a great many, of the air- 

 vesicles coalesce, and large gaps form, so that, in an aggravated case ; 

 the entire lung forms a coarse network. The relaxed, bloodless, dry 

 tissue feels soft as down to the touch ; it is heavily loaded with pig- 

 ment, and is sometimes uniformly black. This deposit of pigment is 

 not a result of extravasation of blood, but is due to pigmentary meta- 

 morphosis of the contents of obliterated capillaries. These nutritive 

 derangements of the pulmonary tissue are essentially like those to be 

 described in the next chapter, as characteristic of vesicular emphysema 

 of the lung, so that the title of senile emphysema is not altogether inap- 

 propriate to the disease in question. In senile atrophy, or senile em- 

 physema, however, the volume of the lung is diminished, while in em- 

 physema, in the stricter sense of the word, it is increased. This impor- 

 tant difference, which furnishes a practical distinction between the two 

 affections, depends upon the difference in the condition of the thorax. 

 The size of the lung manifestly depends upon the capacity of the chest. 

 Now, while in true emphysema the thorax is either in a state of chronic 

 enlargement, or else in a condition of permanent inflation, in senile 

 atrophy the chest is actually contracted, or else it is in a state of per- 

 manent expiratory collapse. The thorax of an old man is shortened by 

 absorption of the intervertebral substance, and laterally compressed by 

 his stooping attitude, and the atrophied muscles of inspiration are inca- 

 pable of dilating it effectively. For a similar reason the heart and li ver, 

 which, in true emphysema, are extensively covered over by the lung, in 

 senile atrophy He in contact with a large part of the thoracic wall. 



This state of the lungs and chest explains why old men become 

 short of breath, why their blood is imperfectly decarbonized, and why 

 they are so apt to look blue about the lips and cheeks. The shortness 

 of breath and the venous state of the blood are due to the diminution 

 of breathing-surface by loss of cell-walls, to a decrease in the number of 

 capillaries, and, finally, to the incomplete manner in which inspiration is 

 effected by the wasted respiratory muscles, and to the absence of that 



