DETERMINING THE STATUS PRAESENS. 



25 



The pleximeter and hammer (plexor) are most commonly used 

 in practice [so-called mediate percussion] as they permit not only 

 of gentle percussion but the part to be examined can be struck a 

 heavy blow which sets deep-lying parts into vibration. The plex- 

 imeter should be so held that its whole surface is in firm contact with 

 the part be percussed. In thin animals the pleximeter should never 

 be applied across two ribs r but should be made to occupy an inter- 

 costal space that the air between it and the body does not modify the 

 sound. The force with which we use the hammer depends upon the 

 thickness of the walls of the part percussed. [In fat animals it is 

 necessary to use more force than in lean ones.] 



Usually two or three strokes, not too close together, suffice to 

 bring out clearly the character of the sound. For comparison it is 

 advisable to percuss corresponding parts on each side of the body. 



For a better conception of the percussion-sound it is advisable 

 to select a suitable place. A room with closed doors is the best; in 

 rooms filled with furniture, or out of doors the application of per- 

 cussion is never satisfactory. 



As a rule large animals are percussed while standing, though 

 small ones may be placed in a recumbent position upon a table. Al- 

 though gentle animals may stand quietly during the operation, very 

 nervous horses or stubborn cows sometimes resist. They can gen- 

 erally be quieted by speaking to them in an assuring tone and by 

 omitting all rough usage of the instruments. 'Dogs and cats may be 

 held by their owners or an attendant. 



---j The Qualities of Percussion-Sounds. 



A body can only then produce a sound when it has lost 

 its equilibrium and vibrates by virtue of its elasticity. Two 

 principles form the basis of percussion : 



1. Solid, airless parts of the body give forth a flat sound 

 of short duration and little intensity. Such a sound is called 

 dull, femoral or flat. 



Fig. 2. 



Fie. 3. 



Fie. 4. 



