440 DISEASES OF THE RESPIRATORY ORGANS. 



which we give to the sound occasionally, not always, heard in 

 the horse's lungs in advanced stages of pneumonia when reso- 

 lution or return to functional activity appears, after absence of 

 sound from inflammatory changes. 



It is not unlike the crepitation rMe now noticed, only it is 

 audible during expiration as well as inspiration ; is of a slower, 

 softer, and irregularly occurring character, not unhke the 

 bubbling of air through mucus or a similar fluid. 



d. Cavernous or Holloiu Rales. — In addition to these sounds 

 now mentioned, which in various moditications are the ordi- 

 nary rattles or rales detected in pulmonary structures under 

 abnormal conditions, there are, as indicated when speaking of 

 changes in pulmonary sounds, some others which are neither 

 so common nor so easily recognised in our patients as in the 

 human subject. The chief are probably those known as 

 'cavernous' or 'hollow rales.' These can only be produced 

 when some cavity, as an abscess, exists, having a free commu- 

 nication with a fair-sized bronchus. The sound heard is 

 either of a gurgling, rattling, hollow, or cavernous character. 



In all cases where these modified rattles could be distin- 

 guished, I have always found that the expired air was impreg- 

 nated with a distinct and often disagreeable odour, and that 

 there was expectoration, at least such as exists in the horse. 

 Also that this cavernous rhonchus has often been associated 

 with the existence in the adjoining portion of the lung- tissue 

 of both ' mucous ' and ' submucous rales.' 



I have not found it, unless following pneumonic disease of 

 some time standing ; indeed, it has always been in connection 

 with gangrene and destruction of lung-tissue. 



D. Friction Sounds, Pleural Sounds. Friction, attrition, or 

 pleural sounds are the names given to sounds only detected 

 in disease, and believed to be associated with the cavity of the 

 thorax, independent of the pulmonary organs. Although it is 

 tolerably certain that in disease sound may be emitted or 

 elicited in connection with the pleural membranes, there is 

 much less unanimity of opinion as respects both the existence 

 of these sounds and the manner of their production than with 

 those we have been speaking of as related to the pulmonary 

 structures. It seems highly probable that it is chiefly, if not 

 solcl}^ during the earlier stages of inflammatory action, or at 



