282 



IiiHanimation. 



sue, with production of spaces filled with pus and confluence of 

 abscesses the condition is called a phlegmon. Where the tissue soft- 

 ening or the gravitation of the pus into dependent positions allows 

 the exudate to escape the abscess is said to break or perforate ; and 

 if in such instances there are formed narrow canals lined with pus 

 and reaching to the surface these are called fistnlcv. A loss of sub- 

 stance upon the external surface or in mucous membranes caused 

 by suppurative destruction of the tissue is known as an ulcere the 

 process as ulceration. 



In chronic suppurations in the zone between the dead tissue 

 breaking down into pus and the normal tissues, there occurs a fibro- 



Fig. 59. 



Section through a calf's kidney ricldlecl witii embolic abscesses ; calyces and pelvis 



full of purulent masses. 



angioplastic proliferation, as a bacony, light gray, firm tissue. The 

 suppurating focus is encapsulated by this demarcating growtli, that 

 is, it is enclosed in an abscess wall, which on its inner surface 

 usually has a grimy, grayish-yellow or slate-gray color. As long as 

 virulent pyogenic bacteria exist in the cavity this abscess membrane 

 continues to give rise to more pus [only in the sense that the exuda- 

 tive processes which underlie the appearance of the leucocytes and 

 fluid are largely going on within it, and not in the sense of a secre- 

 tion as formerly believed] in the focus, for which reason it 

 is sometimes known also as a pyogenic membrane. The involuntary 

 muscle and elastic tissue of arteries exhibit marked resistance to 

 purulent softening; in suppurative cavities, as of the lungs or udder 

 or of a muscular tissue, vessels are often found as bridge-like 



