SUPPURATION. 121 



cells which were originally distributed with tolerable uni- 

 formity through the inflamed parenchyma, forsake their seat of 

 origin, and make their way from all sides towards a central 

 point, which subsequently becomes the purulent deposit (abscessuSy 

 apostema). This migratiou is due partly to the spontaneous 

 motility of the cells, partly to a more or less vigorous transuda- 

 tion from the vessels, which assists their transit and determines 

 its direction towards a common centre. After this convero-ent 

 current has been flowing for a time, the centre in question 

 exhibits a nodular induration. In its interior the vessels are 

 compressed, the parenchyma grows pale, the nutrition of the 

 part ceases with the arrest of the blood-supply ; softening and 

 fatty degeneration set in ; in the transuded fluid the fibres of the 

 connective tissue melt away, and the cells are freed from their 

 connexions. Fluctuation is now perceptible to the finger ; the 

 purulent deposit is formed, or, in surgical phrase, the abscess is 

 ripe. 



Having thus traced the dcvelojjment of an abscess, it seems liardlv 

 necessary to define it as an interstitial cavity in the bod}- containing 

 pus, were it not that purulent accumulations may arise in other 

 ways as well ; these indeed arc not termed abscesses, but they 

 are equivalent to abscesses in a histological point of view ; I 

 allude to purulent effusions into closed cavities, such as serous 

 sacs, joints, mucous bursae, and sheaths of tendons. This 

 extended application of the term corresponds to very wide limits 

 of variation in point of size and form, but it finds its justifica- 

 tion in the identity of their subsequent course. 



^97. By far the most frequent termination of an abscess is 

 its rupture, tlie evacuation of the pus externally. The same 

 forces which brought the pus together continue to push it for- 

 ward in the direction of least resistance. The elastic reaction of 

 parts which enclose the pus, and which it has displaced, operates 

 in the same Avay ; and as the pus (thanks to the very extensive 

 distribution of the connective tissue) is everywhere in contact 

 wdth a tissue susceptible of being itself converted into pus, the 

 pre-eminent frequency of this termination is quite intelligible. 

 The pus then forces its way in the direction of least resistance ; 

 this direction is in the last resort always outwards, the final 

 result being perforation of the cutis, or of a mucous membrane. 

 The matter once evacuated, the cavity of the aljscess becomes a 



