70 INFLAMMATION. 



changes to a soft, impressible, fluctuating tumour. At this 

 stage it contains pus ; which, unless vent be given to it, will 

 accumulate and burst the skin, leaving behind a cavity in 

 which the matter has been lodged. It was this deficiency 

 of substance, probably, that originated the notion of suppu- 

 ration consisting in the dissolution of the solid parts, which 

 (when melted down) became pus. We now regard suppura- 

 tion as a process oi secretion; and^jz^s as a product, the same as 

 the urine or the bile ; and we pretend to know no more about 

 it than we do about the production of these other secreted 

 fluids. In the different textures^ although pus jnay exhibit 

 some diversities in its appearance, yet in most does it evince 

 the same intrinsic properties — possessing globules, resem- 

 bling those contained in the blood, and yielding on its ana- 

 lysis both albumen and fibrin e ; having an identity of com- 

 position with the blood, which induced Laennec to believe 

 that pus was really nothing more than altered coagulable 

 lymph. Be this as it may, it is a fluid produced in the 

 animal economy, though with much more apparent facility 

 in some parts than in others. All unnaturally exposed parts 

 — wounds and abrasions of all descriptions — readily run into 

 suppuration : to them pus seems to form a sort of natural 

 shield highly conducive to their healing operations. Mucous 

 membranes promptly assume the suppurative action : in in- 

 flammation of the bowels we may occasionally detect pus 

 coating the dung-balls. 



Abscess is_, however, a higher degree of elaboration, 

 before suppuration becomes established ; although it is the 

 end for which local inflammation is frequently set up. The 

 cells of the cellular membrane in the beginning become 

 blocked up with coagulable lymph ; in the very centre of 

 which mass, or at the point where the inflammation runs 

 highest granulations are formed : by this is at first secreted a 

 drop of purulent matter; the drop gradually augments, and 

 the surrounding substance is as gradually absorbed ; at length, 

 a cavity containing a collection of pus is formed, or an 

 abscess makes its appearance. 



You frequently find after an abscess has been opened that 



