626 
ON EMPHYSEMA OF THE LUNGS. 
lungs have the appearance of small transparent points, are not 
of an uniform size; the largest are equal to the third or fourth 
part of a millet-seed. They are grouped in masses or lobules, 
divided from each other by partitions of closely condensed cellu¬ 
lar membrane, very thin, yet thicker and more opaque than the 
partitions between the individual cells. These partitions traverse 
the pulmonary substance in all directions, and crossing each 
other under various angles, form figures of different shapes, 
such as lozenges, squares, trapeziums, or irregular triangles, the 
bounding lines of which are rendered still more defined by the 
black pulmonary matter that is deposited along them*. 
If we analyze this structure, we find that it is composed, 1st, 
of the minuter ramifications of the bronchi, which go on sub¬ 
dividing and diminishing in calibre until they terminate each in 
a cul-de-sac or air-cell, as it is commonly termed, of extreme 
delicacy and minuteness, on the parietes of which the pulmo¬ 
nary vessels ramify in an extreme state of fineness! ; and, 2dly, 
of the common cellular membrane which serves to connect these 
air-cells together, and which likewise forms several membranous 
partitions that divide each lobe into a number of distinct lobules, 
and is hence termed the interlobular cellular tissue ; each lobule 
being as perfectly isolated from those adjoining it by this par¬ 
tition, as each lobe is by its investiture of pleura. 
Each of these textures is liable to emphysema, and hence we 
have two varieties of this disease in the lung : 1 . the vesicular 
or true pulmonary emphysema (as it is somewhat arbitrarily 
termed by Laennec), formed by the dilatation of the minute 
bronchi and air-cells, or by the rupture of their parietes, by 
which several contiguous cells are thrown into one ; 2. the in¬ 
terlobular emphysema, formed by the infiltration of air into the 
interlobular cellular tissue. The former usually occurs as a 
chronic disease, while the latter as generally assumes the cha¬ 
racter of an acute affection. 
I. Pulmonary or vesicular emphysema. — In pulmonary em¬ 
physema the size of the air-cells is much increased and is less 
uniform. The greater number equal or exceed the size of a 
millet-seed, while some attain the magnitude of hemp-seed, 
cherry-stones, or even French beansj. We are disposed to 
think, however, that cavities of such a size are rarely formed by 
the dilatation of individual cells, as in more than one hundred 
dissections which we have made of pulmonary emphysema, we 
never, except in one instance, saw the air-cell dilated to the size 
* Forbes’s Translation of Laennec. 
t Reisseisen, De Structura Pulmomim. 
| Laennec. 
