264 Inflammation. 



cells find their way into the part from the lymphatic foci scattered 

 about in all organs. 



Along- with the leucocytes the fluid blood plasma also escapes in 

 greater or less amount from the distended vessels, by a process of 

 leaking through the walls through the openings made by the leuco- 

 cytes and directly through the endothelial cells which have from 

 injury become more readily penetrable; or, as some maintain, the 

 fluid is given off to the tissues as a secretion of the endothelium. 

 It is possible that red blood cells may also escape from the vessels, 

 mixed with the fluid, being passively forced through any existing 

 openings by the extra blood pressure. The transuded blood plasma 

 with its celhflar elements is known briefl\- as the exudate (from 

 e.vsudare, to exude). 



The histological events just detailed place us in a position to 

 understand why and how the phenomena spoken of as the cardinal 

 'symptoms of inflammation are produced. 



The redness (rubor) is the result of the hyper?emia. In earlv 

 stages of the process and in the peripheral zone of an inflammatorv 

 area, where the blood current is accelerated, this hypersemia has the 

 characteristics of an arterial hyperjemia, the vessels showing up 

 conspicuously with a scarlet red color as if injected (injection red- 

 ness, branched redness). The more pronounced the slowing of the 

 current and the more the stagnating blood gives off its oxygen to the 

 inflamed tissue the more the color approximates that of the venous 

 blood, becoming darker and of a more violet hue and becoming 

 more and more dift'use as the dilatation of all the capillaries de- 

 velops. The heat (calor) depends upon the increased rapidity of 

 flow and the volume of arterial blood; the more rapid the current, 

 the less opportunity being aft'orded for loss of heat and the more 

 nearly the temperature of the inflamed part approximates the tem- 

 perature of the blood itself. The heat of an inflamed area is only 

 noticeable on the exterior of the body, in comparison with the parts 

 whose temperature is unchanged, and is not above the temperature 

 of the general blood. The internal organs do not become essentially 

 warmer than the blood, special increase of temperature from meta- 

 bolic changes not taking place in inflamed parts (Perls, Ribbert). 

 [It is claimed by some, however, on the basis of experiments carried 

 on it is true with difficulty and open therefore to a chance of error, 

 that the blood coming from an inflamed part is of higher tempera- 

 ture than that of the arterial blood going to such a part, and that 

 increase of temperature is actually, therefore, produced in inflamma- 

 tion presumably from an increased metaboUsm which obtains.] 



