INFLAMMATION. 143 



cells are massed together and project outward thus replacing 

 the destroyed cells. 



The discharge from such a wound after twenty hours con- 

 sists of serum, shreds and fragments of necrotic tissue, dead 

 cells (especially leucocytes) and a variety of microorganisms. 



The reaction in the above case consists of circulator}- dis- 

 turbances, degeneration, necrosis, and regeneration of tissues. 



Etiology. — The exciting causes of inflammation may act 

 from within the body, hematogenous or lymphogenous, or from 

 without, i. e., extraneous as burning, etc. They may produce their 

 action by direct contact upon surfaces of the body as from a 

 blistering agent externally applied, or, by contact internally, as 

 from arsenic. Thev may produce their effect while being ex- 

 creted, as in the production of nephritis by cantharides or tur- 

 pentine. Some harmless agents may become irritants as the 

 result of chemic change produced by some of the body juices 

 or fluids (lysins). 



The causes of inifammation may be divided into two gen- 

 eral classes, non-infectious and infectious. 



XoN-iNFi-XTious. — The non-infectious causative factors are not 

 as active in producing inflammatory disturbances as the in- 

 fectious agencies, but they are of some importance and should 

 not be overlooked. Some have positively stated that "There 

 is no inflammation without infection." Reasonable interpreta- 

 tions of clinical and experimental observations supply suffi- 

 cient evidence that there is inflammation without infection. 

 The following are the principal non-infectious causes of in- 

 flammation. 



Mechanic or traumatic. SmgicsX wounds which heal by 

 primarv union are undisputed examples of mechanically pro- 

 duced mflammation. The reaction taking place in an aseptic 

 incision consists in cell-destruction, slight circulatory disturb- 

 ances, leucocvtic immigration and regeneration of tissue. Such 

 a reaction is' tvpical of inflammation and the affected area is 

 devoid of any' infection. A sterile needle introduced into a 

 tissue, the surface of which is aseptic, produces a reaction 

 identical to the reaction observed in primary union of tissue. 

 Mechanic or traumatic causes of inflammation may produce, or 

 cause to be produced in the injured cells, chemic substances 

 that are responsible for the reaction. 



Thermic— A temporary exposure to a high or low tem- 

 perature is sufficiently irritating to produce a marked inflam- 

 mation Let those doubting this statement take the chimney 

 from a'lighted lamp and hold it in the hand for one minute and 



