112 
PRINCIPLES OF BACTERIOLOGY 
A very good medium is the glycerin potato. Meat in¬ 
fusion agar with about 10 to 15 per cent of whole blood 
(not defibrmated) is also excellent. 
One of the best media is that of Dorset: 
(a) Carefully break 16 eggs into a flask, shake it 
until the whites and yolks are well mixed. 
(c) Add 100 c.c. of distilled water, strain through a 
sterile cloth. 
(c) Pour 10 c.c. each into sterile test tubes, slant, and 
Fig. 20.—Two types of water-baths. 
put them into an inspissator, sterilizing at 72° C. for 
four hours on two days. 
(d) On third day raise the temperature to 76° C. 
(e) Sterilize in Arnold’s sterilizer at 100° C. for 
fifteen minutes. 
Add two or three drops of sterile water to each tube 
before inoculation. 
One of the new media which is excellent is that of 
Williams and Burdick.* 
*Jour. Bacteriol., July. 1916, i. 
