28o Veterinary Medicine. 



cine Veteriuaire, Lyon), by Freutzel in Germany, and BraCy 

 Clark in England in 1795. It was only, however, after the ad- 

 mirable discoveries of I^aennec that the question was systematical- 

 ly investigated by Delafond, who has furnished the most compre- 

 hensive data on the subject. Out of fifty-four broken-jwinded 

 horses dissected by him no less than forty-five had the lungs 

 extensively emphysematous. This emphysematous lung differs 

 according to whether the emphysema is vesicular or interlobular. 



In vesicular emphysema the smallest bronchial tubes and 

 the air cells have become distended beyond the natural standard 

 and remain permanently so, the lung tissue having lost its power 

 of contraction. If such a lung is inflated and dried, and a thin 

 slice taken from the surface of the emphysematous part the size 

 of the minute orifices on the cut surface will show its condition. 

 These fine openings are only the air cells cut across, and in their 

 healthy state they will admit no larger object than the point of a 

 needle or a fine bristle. They are slightly larger in adult and 

 especially in old horses than they are in the young. If affected 

 by emphysema they will often admit a hempseed or even a small 

 pea. On opening a healthy chest the lung collapses, contracting 

 on itself and expelling, the contained air; if the lung is emphy- 

 sematous the diseased portion does not collapse and if the entire 

 lung is affected it continues to fill the chest and may even bulge 

 outward after it has been opened. The color of the emphysema- 

 tous lung is of a brighter red than are the healthy portions. If 

 a diseased lung has been left exposed to the air for twenty-four 

 to thirty-six hours and then cut across in all directions, the dis- 

 eased lobules may be distinguished at a glance by this lighter 

 shade, and such light portions if near the surface will be found to 

 correspond to elevations above the general level of the lung. If 

 the diseased lung is placed in water it floats on the surface like 

 an inflated bladder scarcely at all sinking into the fluid. If the 

 lung is blown full of air the emphysematous part is first filled 

 causing the bulging on the surface to be still more marked than 

 before. Vesicular emphysema rarely affects an entire lung ; it 

 is usually confined to' the anterior lobas and to the thin lower 

 and posterior borders of the organ. 



Interlobular emphysema is the extravasation of air into the 

 connection tissue between the lobules owing to rupture of the air 



