114 



INFLAMMATION. 



If, however, the animal be allowed to live longer say two or three days 

 before the examination, the condition of the tissue about the growing 

 bacterial mass in the typical course of events shows marked and signifi- 

 cant alteration. Immediately around the bacteria the nuclei fail to take 

 the nuclear stains (Fig. 41); the cytoplasm is unusually granular or 

 fallen into fragments. These are the marks of cell death, and from the 

 situation of this area of dead tissue about the colony of growing bacteria 

 we may infer and the inference is confirmed by a host of tests and ob- 

 servations that, in growing, the bacteria have set free in the tissue about 



:^i|.^SIi^lfllwf /! ".- 



* a - -* *- * " "~ ' : i#.^|f ? % v: v>^' 



>; : .:$||| 3*?$%i 

 ; :'.^!;^ r :^%^^?! 



FIG. 43. NECROSIS AND SUPPURATION IN THE LIVER FROM BACTERIAL INFECTION EXUDATIVE ANI> 

 NECROTIC INFLAMMATION. 



The bacteria are scattered in masses, the liver cells about them are necrotic, while leucocytes have 

 gathered in large numbers within the necrotic area. With slight further disintegration this mass of dt'ad 

 liver tissue and pus cells would form an abscess. 



them some chemical substance whose presence is incompatible with the 

 continuance of the life processes in the liver cells, which in fact has killed 

 them. 



But very soon the tissues near by show a different sort of reaction to 

 this active poison set free upon the spot. Leucocytes gather on the bor- 

 ders of the necrotic area and may form a dense ensheathing mass about it 

 (Fig. 42). If we look for the origin of these, we find that close outside 

 the area of dead tissue and among the gathered leucocytes the smaller 

 blood-vessels are dilated, overfilled with blood, and such marks of the 

 emigration of leucocytes as a tissue removed from the animal and pre- 

 pared for examination may show are unmistakable. ~Not infrequently 



