408 MU. youatt’s veterinary lectures. 
tubercle, but IVlr. Clark, suspecting from its appearance that it 
was not solid, punctured it, and it immediately subsided ; and it 
instantly suggested itself to his mind, that the lungs were in a 
state of emphysema, or that air was contained in a state of extra¬ 
vasation in their substance. Hence Mr. Clark claims the honour 
of being the father of the modern theory of broken wind, and 
which is now adopted by the English and the French schools. 
I do not know, however, why*Mr. Coleman should not partici¬ 
pate in the honour, since he is acknowledged to have suggested 
at the time, that the extravasation of the air into the substance 
of the lungs was occasioned by a rupture of the air-cells. 
Description of the emphysematous State of the Lungs. —In 
almost every broken-winded horse whose carcass I have exa¬ 
mined, I have found these vesicles or vessels (for some of them 
have been of considerable magnitude) on the surface of the lung 
beneath the pleura; and in every case I have been enabled to 
trace them, or a portion of them, into the substance of the lungs, 
and communicating with the air-cells beneath. I have also suc¬ 
ceeded, by gentle and continued pressure, in returning a portion 
of the air again into the lungs, but never in diffusing it among 
the cellular membrane, between the pleura and the lung. I was 
satisfied, therefore, that it was no extravasation of air; that it 
was no gas extricated by any process of decomposition : it was 
simply dilatation of an air-cell, or of some of the air-cells, either 
appertaining to one lobule, or a few contiguous ones. It was not 
extravasation into the parenchymatous substance of the lungj for 
there was no general pulmonary emphysema. It did not resemble 
emphysema in any other part of the frame ; it was nothing like 
that inflation of the cellular membrane, more or less extensive, 
which almost invariably accompanies a puncture into the thorax, 
wounding the lung, and evidently admitting the air into its pa¬ 
renchymatous substance. 
Progress of the Lmphysema and Rupture of the Cells. —I 
have been brought to regard this as the commencement of the 
morbid change in the air-cells, and taking place at different 
periods in different parts of the lungs; for I have invariably 
found some other portions, and more particularly towards tlie 
edges of the lobes, where the cells have not been so much dilated, 
but where they evidently ran into one another. I could there 
press the air along; no, not all over the lobe, but for a little 
space : sometimes, indeed, for the space of an inch or two, but 
oftener not beyond one of the lobules into which the lungs are 
evidently divided ; and while I did this, there was a crepitating 
crackling noise, as if I was breaking down the attenuated mem¬ 
brane of other cells. Here we have the true broken cell, whence 
