14 GENERAL BACTERIOLOGY LESSON 



(a) With a platinum loop remove a little of the culture 

 and place it on a clean slide. 



(b) Add a drop or two of caustic potash (1-5 per cent 

 solution) l and allow this to act for five to ten minutes. 



(c) With filter-paper soak up as much of the caustic 

 potash as possible. 



(d) Mount in Farrant's solution, and examine with a 

 low and a high power, using a narrow diaphragm. 



Make a drawing of the fungus. 



Hanging Drop Cultures 



Make hanging drop cultures of 



'(1) Streptococcus pyogenes. 

 (2) Bacillus filamentosus. 



(a) Take four clean hollow-ground slides. With a brush 

 paint a ring of vaseline around the periphery of the hollow 

 chambers. 



(b) Sterilise four clean cover-glasses by passing them 

 three times slowly through the flame. 



(c) Place the sterilised cover-glasses on a sterilised piece 

 of wire gauze on a tripod and cover it over with a glass globe 

 sterilised by washing it thoroughly with corrosive sublimate 

 1 : 1000. The wire gauze is easily sterilised by heating it 

 to redness over a Bunsen flame. 



(d) With a sterilised platinum loop place a drop of sterile 

 broth or liquid gelatine (or agar-agar) on the centre of each 

 cover-glass, after allowing the cover-glass to cool. 



1 Instead of caustic potash 50 per cent alcohol, tQ which a few 

 drops of ammonia have been added, may be used. 



