CHAPTER IV. 



INFLAMMATION. 

 General Considerations. 



THE conception of inflammation was originally a clinical one in which 

 the process was marked by symptoms redness, heat, swelling, gain, and 

 impaired function. This conception was gradually" enlarged to embrace 

 the new formation of tissue which might be associated with or follow 

 these symptoms, or which might be independent of them. After the 

 knowledge of the importance of the cell became general it was upon the 

 formation and accumulation of cells and other substances that attention 

 was especially fixed. Finally, the processes and structural alterations 

 embraced in the conception of inflammation became so varied and com- 

 plex that a definition or even a characterization seemed not only difficult, 

 but wellnigh impossible. 



It is only within the past decade or two that the processes and lesions 

 involved in inflammation have been seriously considered in the light of 

 comparative pathology and as biological problems divorced for purposes 

 of research from the dominance of traditional clinical conceptions. In 

 view of our increased knowledge of the structure of cells, and of the im- 

 pulses immediate and hereditary which determine their performances, it 

 seems possible now to resolve the complex processes and lesions embraced 

 in the general notions of inflammation into more simple factors, and to 

 arrive, if not at an exact definition, at least at a reasonable conception of 

 the relationship of its phenomena to each other, to those of normal physi- 

 ology, and to other phases of disease. 



\VMth this end in view it seems wise at first to rehearse as simply and 

 briefly as is practicable some of the more typical of the phenomena and 

 lesions which are commonly grouped under the term inflammation. 



While the death of tissue from traunrar and degenerative alterations 

 in the tissues in the presence of various form of poisons are often impor- 

 tant factors in the inflammatory processes, we shall not consider them 

 separately here, because they are incidental rather than inherent and i 

 have already been treated in the section on degenerations and necrosis. 

 But it should be noted that various phases of albuminous degeneration, ' 

 local or general, which are induced by the poisons of the pathogenic 

 bacteria, are very often associated with inflammation, and not infrequently 

 modify, or may even determine, its occurrence. 



A comprehensive survey of the conditions under which inflammation 

 most frequently takes place shows at once that it is almost always asso- 



