INFLAMMATION. 325 



primarily adhesive, passes into the suppurative form. It has 

 been ah'eady shown that this transition is favoured and ushered 

 in (anatomically speaking) by the luxuriant vascularisation of 

 the young false membranes, which furnishes materials for a 

 more exuberant corpuscular proliferation, i.e. for suppuration, 

 wlien the inflamed membrane is exposed to any fresh source of 

 irritation. The practitioner is usually warned of the unfavour- 

 able turn which the disease is taking, by the occurrence of a 

 severe rigor and the hectic fever which follows it. Quite 

 suddenly, as it seems, the cell-proliferation enters upon a more 

 active phase. Every variety of cell, whether it be situated in 

 the exudation, in the false membrane, or in the serous mem- 

 brane itself, takes part in the process. The clear serum becomes 

 turbid. ^Vhole shreds of the false membrane are loosened from 

 their connexion with the underlying tissues and detached, pre- 

 liminary to their liquefaction into pus ; denuded patches of the 

 serous membrane itself undergo losses of substance, which how- 

 ever, are always shallow. Such ulcerations are not uncommon 

 on the costal pleura where it lines the ribs ; they extend into 

 the subserous connective tissue, and more rarely to the perios- 

 teum and bone, which is consequently laid bare and undergoes 

 necrosis. Apart liowever from such accidents, the suppuration 

 retains its superficial character even in its most acute forms. 

 The suppurating surface of the serous membrane is analogous, 

 not to a destructive ulcer, but to a productive and granulating- 

 wound. The analogy with a superficial Avound holds good 

 moreover as regards its limitation on the side of the serous 

 cavity by a membrane of young connective tissue studded with 

 granulations — the '' pyogenic membrane" of authors. The heal- 

 ing process begins in exactly the same way, when the inflam- 

 mation has been of the purulent order from the first. 



In the meantime, an accumulation of pus, often colossal in 

 amount, has been forming in the serous sac. This is not sur- 

 prising when we consider how large a quantity of pus may be 

 secreted even by comparatively small ulcers ; and in the present 

 case vv^e have an ulcerating surface which is measured not by 

 square lines, but by square feet. It is common enough to see 

 half a pailful of pus removed from an empyema by tapping 

 during life or after death. The diaphragm is pushed down 

 together with the liver or the spleen, the intercostal grooves are 



