8i 



the appearance of the cocci both within and outside of the 

 pus cells. 



If from supposed tuberculosis, stain for that organism. 



If from diphtheria, stain for that organism and note the mor- 

 phology of the bacteria. 



If from the pus of an abscess, stain for pyogenic bacteria. 



142. Making cover-glass preparations from pus. 

 Spread as thin a film of the pus as possible on the cover- 

 glass. This can be readily done by drawing the edge of a 

 square cover-glass over the surface of another cover-glass 

 on which a bit of the pus has been placed. See method for 

 making cover-glass preparations from blood ( 104). 



EXERCISE IvL 



A BACTERIOLOGICAL EXAMINATION OF THE SKIN FOR 



MICROCOCCUS (STAPHYLOCOCCUS) EPIDER- 



MIDIS ALBUS. 



143. Explanatory note. There is liable to be on or in 

 the skin a number of bacteria which resist the ordinary 

 methods of cleansing, owing to their being deep seated in 

 the epidermis. The most important among these is M. 

 (Staph.} epidermidis albus. These organisms often infect 

 wounds in surgical operations. An abrasion of the skin with 

 a sterile instrument may be followed by the infection of the 

 wound with this or other species of bacteria which were on, 

 or in the skin itself. The work of this exercise is to demon- 

 strate the presence of these organisms. 



144. General directions. Wash the hands thoroughly 

 with soap and water, using the brush. Then wash them in 

 a solution of carbonate of sodium and rinse thoroughly in 

 boiled water and wipe with a sterilized towel. 



With a flamed and cooled scapel scrape the epidermis over 

 a small area about the finger nails and with these scrapings 



