310 



HISTOLOGY OF THE MORBID PROCESSES. 



tissues in the vicinity may show chiefly necrotic changes ; the 

 tissue will be diffusely stained, the nuclei either unstained, only 

 faintly tinged, or broken into fragments that take the dye in vari- 

 ous intensities (Fig. 274). Around this necrosed tissue there 



FIG. 274. 





Secondary infection of the kidney in a case of erysipelas. (Faulhaber.) a, capillary con- 

 taining streptococci ; b, renal tubule containing a hyaline cast ; c, renal tubule filled by 

 a deposit of calcareous material. In the neighborhood of the capillary containing the 

 bacteria the tissues have been necrosed, and have become reduced to a granular detritus 

 through the peptonizing action of products formed by the bacteria. More remotely, at 

 the upper left, the cells in the renal tubules are in a state of albuminoid degeneration. In 

 this case the bacteria are evidently of great virulence ; probably capable of destroying 

 leucocytes that wandered into their neighborhood, through concentration of the poisons 

 produced ; for the section contains no evidence of a round-cell infiltration with emigrated 

 leucocytes. 



may be a ring of leucocytes, easily identified by their irregularly 

 shaped or fragmented nuclei, which, unless necrosis has taken place, 

 are more deeply stained than the normal nuclei of the surrounding 

 kidney. The central necrosis is due to the poisons that have accom- 

 panied the bacteria at the time of infection or have been subsequently 

 produced by them. Having killed a portion of the tissue through 

 the action of these poisons, the bacteria thrive upon the dead mat- 

 ter and produce fresh poisons, which increase the area of necrotic 



