236 MANUAL OF BACTERIOLOGY. 



the dye diffusely and irregularly, and it exhibits many fine 

 granules. 



We find the cells of the tissues surrounding the necrotic 

 area mingled with large numbers of polynuclear leucocytes, 

 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 parts (frag- 

 mentation), which indicates the commencement of their 

 destruction. In sections through small abscesses it is pos- 

 sible, by means of a double stain of carmine followed 

 with gentian-violet, according to 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 num- 

 bers, even making masses visible with a low power of the 

 microscope. Preparations, most convincing and of great 

 beauty, may be secured in this manner. It is often pos- 

 sible to demonstrate masses of micrococci filling up the 

 lumina of capillaries in which they are lodged as emboli. 



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 polynu- 

 clear leucocytes are found floating, and they constitute the 

 greater part of the so-called pus-cells. The nuclei of 

 these cells are obscured 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 consist 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 in laboratory experi- 

 ments by the introduction of sterilized irritants, such as 

 croton oil, in the vast majority of cases suppuration is due 

 to the action of pyogenic bacteria. 



