Signs of IiiflaDiiiHition. 265 



The szi'dliiig (tumor) of an inflamed tissue is easily comprehended. 

 The exudate fills up the lymph spaces and stretches the structures 

 apart ; the vessels are dilated, and the lymph is prevented from es- 

 caping readily from the tissue because of loss of elasticity of the 

 interstitial substance (Landerer). In consequence a turgescence, 

 appreciable as an oedematous swelling in inflamed areas on the 

 periphery of the body, occurs. In chronic inflammations the con- 

 nective tissue proliferation gives to the organ or its connective 

 tissue frame-work more or less increase of volume. The pain 

 (dolor) is attributable to the pressure exerted by the exudate and 

 swollen tissue upon the sensory nerve filaments, or to direct irrita- 

 tion of the latter. In addition this fault interferes with the trans- 

 mission of nervous impulses, in consequence of which arises 

 functional disturbance, in addition to the disturbance occasioned by 

 the primary influence of the cause of the inflammation (death of 

 tissue) and the simple mechanical disturbances produced by the 

 collection of exudate in cavities (as the air spaces of the lung or 

 the pleural cavities), the overgrowth of tissue, etc. 



As already stated, the processes involved in inflammation are 

 nothing but modifications of physiological processes. Exudation of 

 plasma and leucocytes and their movement through the tissues are 

 continuallv going on under normal conditions ; the ordinary lymph 

 formation is the result of a normal process which in inflammation 

 is clearlv only exaggerated. The reason for this heterometria. 

 and more particularly for the circulatory disturbances, may be found 

 in certain physical and chemical changes in the vessel wall. All 

 inflammatory excitants apparently exert, directly or indirectly, 

 chemical influences leading to changes of the endothelium of the 

 vessels and thus making the vessel wall more permeable than nor- 

 mally. It can be shown for example that the endothelial cells may 

 be caused to shrink, contract into spherical form, and thus give rise 

 to imperfections in their interstitial cement. These openings pro- 

 duced pathologically facilitate the leakage of the plasma and the 

 emigration of the leucocytes through the wall and make it possible 

 for the red cells to undergo diapedesis. Changes in the tension 

 of the vascular wall, relaxation of the arterial musculature, neces- 

 sarily accompany lesions of the endothelial cells and the surrounding 

 tissues, and this in turn occasions dilatation of the vessels. In every 

 case, too, the nervous system, especially the network of vasodilators 

 and vasoconstrictors distributed about the vessels, takes part in 

 bringing about the vascular dilatation, these nerves being affected, 

 irritatecl or paralyzed, by the original cause of the inflammation. 



