148 GENERAL MICROBIOLOGY 



EXERCISE 52. QUALITATIVE STUDY OF THE MICRO- 

 FLORA OF THE SKIN AND HAIR IN HEALTH AND 

 IN DISEASE 



Apparatus. Ordinary forceps; two sterile, small white 

 enamel basins (steam-sterilized); three sterile 1 c.c. pipettes; 

 six sterile Petri dishes; six tubes of sterile agar; one liter 

 flask containing about 700 c.c. of sterile water or salt 

 solution; sterile cloth (J yd. hospital gauze wrapped in 

 paper and sterilized at 180 C.); soap; clean slides and 

 cover-glasses. 



Method. I. Skin, (a) Normal. 1. Place about half 

 the sterile water in a sterile basin. 



2. Wash the hands thoroughly in the sterile water. 



3. Plate 1 c.c. of this water immediately in ordinary 

 agar. 



4. Then wash the hands well with soap and tap water, 

 rinse with tap water till free of soap and dry the hands on 

 the sterile cloth. 



5. Place the remaining sterile water in the second 

 sterile basin and wash the hands again. 



6. Plate 1 c.c. of this water. 



7. Incubate both plates (inverted) at 37 C. 



8. How long before starting this experiment did you 

 wash your hands? How might this influence your results? 



9. What types of microorganisms would you expect 

 to find on the skin? Why? 



(6) Diseased. 1. With a sterile needle obtain a small 

 amount of purulent material from a pustule, boil, or abscess, 

 etc. 



2. Make three loop-dilution plates in agar. Incubate 

 at 37 C. 



3. Examine some of this material microscopically by 

 preparing a stained smear. 



4. Draw and describe the latter. Do you find the 

 same organisms on the plates as on the slide? 



