REMARKS ON EMPHYSEMA OF THE LUNGS. 
283 
emphysema was very frequently hereditary. And Louis has 
since found that emphysema often develops itself without pulmo¬ 
nary catarrh. Dr. Budd considers dilatation of the air-cells, like 
dilatation of the chest, a necessary consequence of want of elasti¬ 
city in the lung, which he regards as the fundamental and pri¬ 
mary character of emphysema. 
Dr. Budd gives an account of flie state of the lungs in twenty 
horses of various ages; from the dissection of which he concludes 
emphysema of the lungs in them to be very common, and that it 
follows, in all particulars, the same order as in man. He infers 
from this, that the disease has the same cause in both ; and that 
in horses, as in man, it is very frequently hereditary. 
Dr. B. speaks throughout of the “vesicular emphysema.” What 
has been called “ interlobular emphysema,” i. e. extravasation into 
the cellular tissue of the lung, rarely exists to such a degree as 
to give rise to any symptoms, or to merit being considered as a 
disease. It is the result of an accident, viz. rupture of the air-cell, 
most commonly caused by a deep and rapid inspiration, and which 
is, generally, a very trifling injury: the density of the cellular 
tissue of the lung preventing the extravasation taking place to any 
great extent. 
Dr. Johnson inquired how Dr. B. reconciled his opinion, “ that the 
bronchial tubes, although elastic, were not contractible,” with a fit of 
asthma, its relief and recurrence. Dilatation of the air-cells did not 
always occur as a sequence of asthma, but might be found where 
that disease had never existed. He had seen the air-cells dilated 
from the size of a pea to that of a pear, in a person who had for 
several years an habitual dyspnoea. The lungs of the great Dr. 
Johnson were similarly diseased, and yet he was not at all asth¬ 
matic, his breath failing him only when he climbed high mountains. 
Sir B. C. Brodie observed that it was difficult to distinguish 
cause from effect. Was it is not possible the dilatation might be 
the effect rather than the cause of asthma. He had a boy who died 
from hydrophobia, suffering violent spasms of the glottis, in whom 
the air-cells were found dilated in the shape of small bladders. 
They were not supposed to have been so before the hydrophobia, 
but were thought to have been the result of the difficult respiration 
consequent upon the spasm of the glottis. He also knew a gentle¬ 
man who had had spasmodic asthma for years at intervals, but was 
now free from it. If dilatation had been the cause, the cells must 
have gradually resumed their natural size. On dividing the eighth 
pair of nerves of animals, he had been struck with the resemblance 
of the symptoms produced to spasmodic asthma. The animals 
breathed with great voluntary effort, and could not go to sleep, 
which he was led to attribute to the sympathy between the lungs 
