MICROCOCCUS PYOGENE8. 187 



nizing and a predisposing substance, the former being precipitated and 

 the latter soluble in alcohol. Tavel was, however, unable to produce 

 immunity with the alcoholic precipitate, the animals either dying 

 from chronic intoxication or succumbing to an additional injection 

 with virulent cocci. 



The serum of actively immunized animals has no noticeable effect 

 upon the Micr. pyogenes in vitro; it is also, so far, of scarcely any 

 practical value for producing passive immunity. 



Special Culture Methods. Isolation is accomplished 

 most rapidly by means of agar plates at incubator tem- 

 perature. The potato culture is best for the study of the 

 chromogenesis. Milk cultures and animal investigations 

 are necessary. 



Micrococcus pyogenes f albus (Rosenbach). 



In all respects like the Micr. pyogenes aureus. See 

 Plate 9, i and ir, and the remarks on page 181. 



Here belongs the Micr. urese liquefaciens Fliigge (com- 

 pare page 71). 



Micrococcus pyogenes /? citreus (Passet). 



We have studied this organism only in a culture ob- 

 tained from C. Frankel, and designated by him as identi- 

 cal with the Micr. flavus (page 178). It did not coagu- 

 late milk and produced a slow liquefaction of gelatin with 

 formation of air-bubbles. A Micr. pyogenes citreus is 

 said to exist, however, which corresponds entirely with 

 the Micr. pyogenes aureus except in the color. With this 

 the results of cultures by R. 0. Neumann agree (page 

 181). 



Varieties Closely Related to or Identical with the 

 Micrococcus pyogenes Ros. (Lehm. and Neum.). 1 



Micrococci in Variola. 



Vanselow and Czaplewski (Vierteljahrsschr. f. gerichtl. Med., 1899, 

 Heft 1) believed they had found an organism closely connected with 

 the variola process in what was previously named by Klebs the Micr. 



1 The old names, Staphylococcus cereus flavus and Staph. cereus 

 albus Passet, can not be sharply defined, and can well be dispensed 

 with. "These varieties are rarely cultivated from pus and grow upon 



