282 Veterinary Medicine. 



Dilatation of the smaller bronchial tubes is frequentlj^ present 

 and especiall}^ characterises such cases as supervene on chronic 

 bronchitis. These dilated tubes contain a plastic, whitish, inodor- 

 ous mucus. 



Another frequent concomitant of the emphysematous lung is 

 a dilatation of the right cavities of the heart, especially the auricle, 

 and an attenuation of their walls. The same condition is noticed 

 in pulmonary emphysema in man and like this is probably due to 

 the slow and imperfect circulation in the diseased lung. 



Collating these structural changes with the different causes of 

 the disease we find that they harmonize with the theory of im- 

 paired function on the part of the vagus nerve or its presiding gan- 

 glia, whether this functional disturbance has its origin in disorder 

 of the digestive organs, as in the great majority of cases, in severe 

 muscular efforts, or in chronic bronchitis. 



Section of the vagi nerves affords an exaggerated instance of 

 their paralysis and its results. These are mainly emphysema, 

 capillary dilatation, blood extravasation, inflammation arid pul- 

 monary collapse. Emphysema is the first result and due to the 

 slow, deep respiration (Boddaert) and loss of contractibility 

 (lyonget) ; capillar}^ dilatation results from the extreme distension 

 of the air cells and the retention in them of air highly charged 

 with carbonic acid (Bonders) ; the other lesions occur later and 

 own very different causes. 



That this is the true nature of the disease would further appear 

 from the occurrence of emphysema without broken wind, two 

 cases of which are recorded by Percivall ; and from the existence 

 of broken wind without emphysema. Cases of this last variety 

 have been recorded by Godine, Volpi, Rodet, D'Arboval, and 

 Delafond in France ; and by Sewali, Dick, Smith, Hallen and 

 Gloag in Britain. In connection with this last class of cases it 

 must be noted that dilatation of the right cavities of the heart 

 sometimes gives rise to very similar symptoms, and that the signs 

 of chronic bronchitis are often scarcely distinguishable from those 

 of broken wind. In catarrhal bronchitis too, after the air tubes 

 have been washed, it is sometimes impossible to decide whether 

 the lining membrane has been the subject of inflammation or not. 



Syynptoms. The most prominent are the double lift of the flank 

 with each expiratory act, in the absence of fever, the short, weak. 



