BROKEN-WIND. 161 



itself becomes raised by the air underneath. Pierced with 

 a pin these Httle bladders^ as well as some of the neigh- 

 bouring vesicles, empty themselves completely. Moderate 

 insufflation of the lung expands simultaneously the pulmonary 

 vesicles and meshes of the cellular tissue; more force sends 

 the air underneath the pleura, and produces large bladders 

 along the borders and extremities of the lobes. 



Inter-lobular emphysema is often combined with air-cell 

 dilatation, sometimes with bronchial dilatation, rarely with 

 varico- aneurism al dilatation of the small vessels underneath 

 the pleura. 



The English history of broken-wind will be found 

 meager compared with the continental. Most of our earlier 

 writers on farriery derived their explications of its pathology 

 from human medicine; while the moderns, with few ex- 

 ceptions, have embraced the doctrine of emphysema. 



The doctrine of ruptured air-cells, according to 

 Mr. Bracey Clark, originated in this way: — "In the year 

 1795, being engaged in the dissection of a grey mare sent 

 to the Veterinary College to be destroyed on account of this 

 complaint, on opening the chest, the lungs appeared free 

 from inflammation, being very white : and, as they appeared 

 free from redness and increase of colour, the general conco- 

 mitant of disease, we were led for awhile to consider the 

 lungs as not the seat of the disorder, as others had done (for 

 several pupils were present at the dissection). On cutting 

 into their substance, no inflammation was perceivable. On 

 examining them more closely, we observed a small bladder 

 or vesicle on the outside of the lungs, in the external 

 investing pleuritic coat : this was conceived by some who 

 were present to be a tubercle, and that tubercles might be 

 the cause of broken-wind. Suspecting, however, from its 

 appearance that it was not solid, but contained air, it was 

 punctured, when it immediately subsided. This instantly 

 suggested to the writer (Mr. B. Clark) that the lungs were 

 actually in a state of emphysema^ or that air was contained in 

 a state of extravasation within their substance; and which not 

 only seemed evidently the case in this instance, but which we 

 II. ' 11 



