302 



HISTOLOGY OF THE MORBID PROCESSES. 



of 'the different constituents in the extidate. The general nature 

 of the process is the same in all cases. 



We are now in a position to explain four of the cardinal symp- 

 toms of acute inflammation. The increase of temperature and the 

 redness (calor and rubor) are attributable to the hypersemia of the 

 part and its surroundings. The swelling and pain (tumor and 

 dolor) are caused, at least chiefly, by the presence of the exudate. 

 The suspension of function, or fifth cardinal symptom of acute 



FIG. 268. 



d e f 



Section from lung in the second or exudative stage of croupous pneumonia : a, endothelial 

 wall of a small vein ; &, blood within the vein, unusually rich in leucocytes, which have 

 collected during the slowing of the circulation. The line 6 points to the nucleus of a 

 leucocyte. Part of the blood has fallen out of the section during its preparation, c, leu- 

 cocytes beneath the endothelixim of the vascular wall ; d, cedematous fibrous tissue sur- 

 rounding the vessel. The fibres of the tissue have been separated by the exuded serum. 

 This tissue is also moderately infiltrated with leucocytes that may have passed through 

 the walls of the vein, and contains a few red blood-corpuscles, e, wall separating two pul- 

 monary alveoli. This is also somewhat infiltrated with leucocytes. /, exudate within an 

 alveolus, consisting of serum, fibrin, leucocytes, and red blood-corpuscles ; it also con- 

 tains a few epithelial cells desquamated from the alveolar wall, g. 



inflammation, may have a more complex causation. It may be due 

 to the immediate effects of the injury that occasioned the inflam- 

 mation, to disturbance of nutrition, to the presence of the exudate, 

 or perhaps to an interruption of the normal nervous mechanism. 

 All these disturbing factors are present, and may vary in their 

 potency in different cases. 



All the changes that have been hitherto described are the imme- 

 diate or only slightly remote effects of the damage to the tissues, 

 and have nothing to do with the process of repair. They may be 



