EXERCISE XXVII. 



STUDY OF CERTAIN PYOGENIC BACTERIA. 



92. Explanatory note. There are a number of bacte- 

 ria which are able to cause suppuration but ordinarily the for- 

 mation of pus is due to the presence of streptococci and mi- 

 crococci. As it is impossible to study more than a very few 

 of these species two of the most common and one more rarely 

 {Bacillus pyocyaneus} encountered organism in suppurating 

 wounds and abscesses are chosen. 



93. General directions. Inoculate a "set of media " 

 from each of the cultures of the following bacteria which 

 will be furnished. Streptococcus pyogenes, Micrococcus 

 pyogenes aureus^ and Bacillus pyocyaneus (bacillus of green 

 pus). 



Read carefully the chapter on pyogenic bacteria in the 

 text-book. 



EXERCISE XXVIII. 



PYOGENIC BACTERIA (continued). 



94. General directions. Examine and carefully 

 describe the cultures made in Exercise XXVII. Note 

 especially the growth on the agar, gelatin, potato, and in 

 the fermentation tubes. In describing the color use color 

 charts which are in the laboratory. 



Examine microscopically in (i) hanging drop, and (2) 

 stained (alkaline-methylene-blue) cover-glass preparations 

 the bacteria from each of the bouillon and agar cultures. 



Measure a few of the bacteria in the stained preparations 

 from the agar cultures and make a drawing of them, magni- 

 fied 1000 diameters. 



