24 CLINICAL DIAGNOSTICS. 



2. A part is firm when it is of the consistency of normal 

 liver. According to the part's resistance to the touch it may be 

 firm, tendinous, solid. A cellular infiltration of tissues 

 (phlegmon) or the presence of neoplasms made up of cells, 

 will lend to a part a firm consistency (connective tissue). 



3. A part is hard when of the consistency of bone. 



4. A part is -fluctuating when it is soft, elastic and undu- 

 lates on pressure. Only fluids admit of such a rapid trans- 

 mission of pressure (pus, blood, lymph, serum). If the 

 tissue surrounding the fluid is not tense, waves are seen to 

 pass over the surface of the swelling (true or soft fluctuations). 

 Soft-elastic (fat) tissue or tissue impregnated with a quantity 

 of fluid may also show fluctuation ; this undulating consistency 

 is spoken of as pseudo-fluctuation. 



5. A part is emphysematous when it presents a puffy 

 swelling which crackles and shifts on palpation; it is due to 

 the presence of air or gas in the tissue (emphysema). 



3. Percussion. 



By percussion we understand striking the surface of the 

 animal body so that the parts thus set in vibration emit audi- 

 ble sounds. The "percussion-sound" thus produced will differ 

 with the physical condition of the vibrating parts, and these 

 differences are so well marked that definite conclusions can be 

 drawn from them. 



Methods of percussion. Percussion can be practiced without 



the use of instruments [so-called immediate percussion] on small ani- 

 mals or large animals thin in flesh. The index or middle finger of 

 the left hand is held firmly against the part to be percussed and struck 

 with the middle finger of the right hand. The striking finger should 

 be held somewhat curved and stiff. The advantage of immediate per- 

 cussion lies in the facility with which the finger may be placed 

 between the ribs and amid the long hair of some dogs and the wool 

 of sheep. By this method the sense of hearing is further greatly 

 assisted by that of feeling. For the larger animals the sounds ob- 

 tained from this finger-to-finger method of percussion are not definite 

 enough for practical use. 



In the immediate method of percussion, however, the sound 

 can be augmented by employing the percussion hammer to strike 

 the finger which is applied to the part (finger-hammer percussion). 



