130 



CLINICAL BACTERIOLOGY. 



Microscopic Arrangement of the Streptococci in the 

 Invaded Skin. As suggested by Fehleisen, three zones 

 may be distinguished : ( I ) A central, in which the process 

 is in retrogression ; (2) the elevated erysipelatous margin ; 

 and (3) a peripheral zone surrounding this deeply red ery- 

 sipelatous zone, which, microscopically, is apparently still 

 completely normal. Streptococci are found in each of 

 these three zones, but in much the largest number in the 

 erysipelatous margin and in smaller number in the central 

 and in the peripheral zone. The organisms lie in the 



Fig. 46 Streptococcus erysipelatis, seen in a section through human skin ; X soo 

 (FrankelandPfeiffer). 



lymph-spaces and the lymph-vessels of the skin and the 

 subcutaneous fatty tissue ; the lymph-spaces are almost 

 completely choked up by them. Sometimes they collect 

 also about the lymph-vessels and the blood-vessels. In 

 the vesicles in cases of erysipelas bullosum streptococci 

 are not constantly present. On the other hand, they are 

 never absent from the purulent products of phlegmonous ery- 

 sipelas. As a rule, in cases of erysipelas pursuing a favor- 

 able course the streptococci do not gain entrance into the 

 blood. Metastases are, therefore, rare in the symptom- 



