CHAPTER VI. 



PUS. 



SEC. 1. INTRODUCTORY REMARKS ON THE PHYSICAL PROPERTIES 

 OF PUS AND ON THE NATURE OF PUS. 



CLOSELY connected with the liquids which have been considered in 

 the preceding chapter is one which, unlike these, forms no part of 

 the healthy body, but is invariably the result of a morbid process. 



Pus is sometimes found in one of the natural cavities of the body, 

 as, for example, within the interior of a serous sac : sometimes 

 covering an epitheliated surface on the exterior, or opening on the 

 exterior, of the body : most commonly contained within an abscess 

 a cavity whose walls are constituted by inflamed and usually indu- 

 rated tissues. 



Physical Fresh, healthy, laudable pus presents the appear- 



characters. ance of a somewhat creamy yellow liquid, which 

 unless it have been obtained from the vicinity of the intestines, is 

 destitute of fostid odour and possesses, at most, a mawkish smell. 



Its reaction is usually said to be alkaline, but, according to Ewald, 

 it is often acid. Its specific gravity varies between 1020 and 1040, 

 being on an average 1032. The fluid does not coagulate spon- 

 taneously. 



Microscopi- Under the microscope pus is seen to be composed 



cai charac- of a clear liquid the pus serum in which closely 

 ters * float a large number of cells which, when first formed, 



resemble, if they are not identical with, the colourless cells of the 

 blood. 



These cells are usually more or less spherical : destitute of a cell 

 wall : somewhat granular, and contain one or more (often three, some- 

 times more) nuclei, which are rendered evident by the action of acetic 

 acid, which causes the protoplasm of the cell to become transparent 

 and indistinct. When very young, pus cells may exhibit amoeboid 

 movements, though the opportunity for observing this phenomenon 

 does not often present itself. 



The diameter of pus corpuscles usually varies between 8/j, and 

 by the action of water they swell and become transparent, 



