234 MANUAL OF BACTERIOLOGY. 



or takes the dye diffusely and irregularly, and it is broken 

 up into fine granules. 



The cells of the tissues surrounding the necrotic area are 

 mingled with large numbers of polynuclear leukocytes, which 

 enclose the area of irritation. 



The nuclei of the cells near the center of the abscess are 

 frequently broken up into a number of small fragments, which 

 indicates the commencement of their destruction. In sections 

 through small abscesses it is possible, by means of a double 

 stain of carmine, followed by Gram's method, to bring out 

 the histological character of the tissue, and at the same time 

 to stain the common pyogenic bacteria, which are usually 

 found near the center of the abscess in large numbers, even 

 making masses visible with a low power of the microscope. 

 It is often possible by this method to demonstrate masses of 

 micrococci filling up the lumina of capillaries in which they 

 are lodged as emboh. 



The production of pus in the center of the abscess is due 

 to the liquefaction of the necrotic tissue, which apparently 

 results from the action of some peptonizing ferment. In the 

 liquid thus formed immense numbers of the polynuclear leuko- 

 cytes are found floating, and they constitute the greater part 

 of the so-called pus-cells. The nuclei of these cells are ob- 

 scured by clouds of extremely fine granules. The granules are 

 of an albuminoid nature, and are dissolved by acetic acid, 

 when the nuclei become visible. The nuclei generally con- 

 sist of three, four, five or more portions. The presence of 

 the fine albuminoid granules in the pus-cells is to be counted 

 as a degenerative change. Although it is possible to produce 

 suppuration experimentally by the introduction of sterilized 

 irritants, such as croton oil, into the tissues of animals, in all 

 cases met with in practice suppuration is due to the action 

 of pyogenic bacteria. 



Specimens of pus will nearly always be found to contain 



