MICROFLORA OF THE SKIN AND HAIR 149 



6. Isolate the most predominant organism on the plates 

 and identify them. 



6. What is the source of all these microorganisms? 

 What becomes of them when we wash our hands and wipe 

 them in the ordinary way? Are they detrimental to health? 



7. What is pus? Of what does it consist? What care 

 should be taken with discharges from suppurating sores? 



II. Hair, (a) Normal. 1. Using flame-sterilized forceps 

 (ordinary type), obtain several hairs and place them in a 

 sterile Petri dish. 



2. Using a sterile pipette, add 1 c.c. of sterile water 

 or salt solution to the Petri dish and stir the hairs about 

 in it with the pipette or sterile loop in order to dislodge the 

 organisms adhering to them. 



3. Pour into the plate a tube of melted agar (at 40 

 to 45 C.), and when hard, incubate at 37 C. 



4. After twenty-four to forty-eight hours, examine 

 predominating colonies in a hanging drop. 



(b) Diseased. 1. With sterile forceps obtain a few hairs 

 from the growing edge of the infected portion of the skin 

 affected with ringworm or barber's itch. These .hairs will 

 come out easily in comparison with healthy hairs. 



2. Mount and examine for the fungus, Trichophyton 

 tonsurans. (See illustration on p. 578 in Marshall's 

 Microbiology.) Draw. 



3. Continuous application of a glycerinated solution 

 of 1 : 500 HgCl 2 (glycerin 1 part, HgCl 2 1 : 500, 9 parts) 

 will kill this fungus. 



State in detail your results for I and II, draw any con- 

 clusion permissible and point out any practical application. 



REFERENCES 



MARSHALL: Microbiology, pp. 522-524, 545, 578, 591-593. 

 BESSON: Practical Bacteriology, Microbiology aud Serum Therapy, 

 pp. 679-688. 



