ON EMPHYSEMA OF THE LUNGS. G31 
of some chronic affections of the bronchial tubes, such as dry 
catarrh, asthma, or the congested state of the mucous mem¬ 
brane, so frequently produced by organic lesions of the heart; 
it may likewise be produced in a very short space of time, when 
the efforts made by the muscles of respiration are violent and 
constantly repeated. We have frequently found the lungs em¬ 
physematous in children dying of hooping-cough; and in one 
instance, where the hooping-cough had not lasted longer than 
three weeks, we saw several cells dilated to the size of garden- 
peas, of a globular form, and with their parietes evidently hy¬ 
pertrophied. 
From whatever cause the emphysema proceeds, its constant 
effect is to render the portion of lung affected incapable of per¬ 
forming its respiratory functions, as is evident from the absence 
of respiratory murmur in the part during life, and the difficulty 
with which the air escapes from the overstrained or ruptured 
cells, even after the lung has been removed from the body. 
Moreover, as the emphysema is in almost every instance origin¬ 
ally produced by turgescence of the bronchial membrane, or 
spasm of the circular fibres, so from an effect it generally be¬ 
comes a cause, and maintains the disease by which it was 
originally excited. Accordingly we find that persons labouring 
under emphysema of the lung are particularly liable to attacks 
of asthma and bronchitis ; and, as a consequence of the latter, 
and of the efforts made during respiration, to hypertrophy or 
dilatation of the heart. These intercurrent diseases usually 
occur only after long intervals during the first years of the dis¬ 
ease ; but when the complaint is of long standing, and the 
patient is far advanced in life, the paroxysms become more fre¬ 
quent and more severe ; each succeeding attack increases the 
extent of the organic lesion and rupture of the pulmonary tis¬ 
sues, and sometimes interlobular emphysema then ensues. 
From these observations it may be concluded that pulmonary 
emphysema in a moderate degree is not a disease of great 
severity, and that the principal danger is to be apprehended 
from the repeated attacks of bronchial disease by which the 
emphysematous condition of the lung was originally produced, 
and to which, in its turn, it seems to act as a predisposing 
cause. 
From the pathology of emphysema, its diagnosis and treat¬ 
ment may be easily deduced. The dyspnoea, which is its most 
constant symptom, depends in a great measure on the extent of 
the disease, and the age and constitution of the individual. 
When the emphysema is rapidly formed, occupies an extensive 
portion of the lung, and occurs in a young plethoric subject, 
