62 
THOUGHTS ON BROKEN WIND. 
“ Again; when the air has accumulated in the lung, it is with 
difficulty expelled. There are direct obstacles to its outward 
passage in the altered condition of the mucous membrane of the 
tubes, and in the accumulation of secretion in them. Moreover, 
the expelling force is, in great part, due to the re-action of the 
elastic tissue, which enters largely into the formation of the 
bronchial tubes, and which invests the lobules of the lung. 
But the undue stretching to which this tissue has been sub¬ 
jected, not only from the forced inspiration, but from the de¬ 
tention of the air within the lungs, and the accumulation of 
mucus in the tubes, must, as the disease advances, more or less 
impair its elastic power, and therefore weaken the force which 
takes the most direct and the largest share in the process of 
expiration. Thus, the longer the duration of the disease, and 
the more frequent the attacks, the more serious will be the 
evils which follow in its train. 
“You may readily gather from what I have said, what are the 
alterations in the lung which chronic bronchitis tends to produce. 
They are, first, the immediate changes; and, secondly, the re¬ 
mote ones. The immediate changes are those which affect the 
mucous membrane and muscular fibres of the bronchial tubes, 
as well as the tubes themselves; such as inflammation, thicken¬ 
ing, altered secretions, perhaps even ulceration, and also more 
or less dilatation of the tubes. The remote changes are, a still 
further dilatation of the tubes—a dilatation of the air-cells; and 
when that dilatation goes beyond a certain point, a stretching, 
and even a rupture, of many of the bands of elastic tissue which 
are found in the lobules. This stretching of the bronchial 
passages and cells gives rise to a corresponding change in the 
air-cells, which exercises a very marked influence upon the 
capillary vessels of the lung, which, so far as I know, was first 
pointed out by Mr. Rainey, of St. Thomas’s Hospital. The 
expansion of the air-cells causes an extension of the meshes of 
the capillary net-work distributed upon and within them; and 
the rupture of many of the intersecting bands of fibrous tissue 
causes obliteration of their bloodvessels. Thus, the capillary 
system of the lung becomes diminished in its capacity; and thus 
is explained the fact, long known, that emphysematous lungs are 
apt to be pale, and to look as if they contained but little blood. 
“ Now, the state to which the lung is thus brought by a long 
continuance of chronic bronchitis, is that which we call em¬ 
physema, in which there is more or less dilatation of a greater 
or less number of air-cells, and a consequent diminution in the 
area of the capillary system belonging to them.” 
The diaphragm is most frequently found pale and attenuated, 
and sometimes ruptured. In cases of long standing, this muscle 
