TtESPIRATORY APPARATUS. 123 



e n t in the IniT^s : g-landers, tuberculosis, carcinoma, sarcoma, 

 echinococci, etc. 



3. If an airless, s o 1 i d m e d i u m c o m e b e - 

 t ween the 1 u n g and the p 1 e x i m e t e r . 



Inflammation, swelling- of the thoracic wall (after mus- 

 tard applications) ; neoformations on the pleura; collection of 

 considerable fluid exudate or transudate in pleuritis. conta- 

 gious pleuropneumonia of the horse, contagious pleuro- 

 pneumonia of the ox, and in swine plague. In the horse the 

 presence of but a few litres of fluid in the chest cannot usually 

 be determined. 



Pleuritic dullness is characterized by its ]iori::onial upper 

 boundary which shifts if the position of the body is changed, 

 the contained fluid seeking the lowest level. This latter is 

 most marked in small animals. 



The tympanitic percussion sound is abnormal 

 when it occurs in the thorax. It appears : 



1. In collapse of the pulmonary tissue 

 from a retraction of the lungs in the presence of pleuritic exu- 

 date. The collapsed lung floats upon the exudate, hence above 

 the 'horizontal line of dullness a tympanitic zone exists. 



a. In the first and last stages (resolution) of pneumonia. 



b. If numerous, small tumors occur in the lungs and the 

 pulmonary tissue amid them is collapsed. 



2. If caverns, or large bronchiectases 

 [morbid dilatations of the bronchi] are present in tl:: L:ngs. 

 The intensity and clearness of the tympanitic tone depends 

 upon whether the cavities momentarily contain air or exudate. 



The tvmpani:;ic percussion sound has a metallic tinkling, 

 tone wl'.en t!:e v/r.Ils o£ the cir-ccntaining cavity are smooth 

 and distended. 



Tlic cracked-pot resonance. [This resembles the sound 

 produced by striking the hands, loosely folded across e.vh 

 other, against the knee, tlie contained air being suddenly forced 

 out between the fingers — Loomis]. It occurs in t'le thorax 



