I30 LABORATORY GUIDE IN -BACTERIOLOGY 



Yeast-water. — i liter of washed yeast or i pound of pressed 

 yeast is boiled with 2 liters of water for i hour. The reaction 

 is made neutral to phenolphthalein, and the solution is filtered 

 until clear, and sterilized in Arnold for 3 consecutive days. 



Dextrose-yeast-water. — 10-15 per cent, dextrose is dissolved 

 in yeast-water without adjusting the reaction. 



Egg medium (Dorset). — Eggs are broken into a flask, and 

 the yolks are broken with a platinum wire. Then the flask 

 is gently shaken, so as to mix the yolks with the whites without 

 causing foam to form. 10 c.c. are distributed in culture- 

 tubes, and then the medium is hardened in a sloping position 

 in the Koch inspissator for 2 successive days for 4 or 5 hours 

 at 70°. 



Egg-yolk medium (Dorset). — Add 5-10 c.c. of sterile water 

 to the yolks of 3 or 4 eggs, and then pursue the same course 

 as in the other egg medium. 



Egg-yolk medium (Capaldi). — A few loopfuls of egg-yolk 

 are added to a tube of liquefied agar cooled to 45-47°. 



Enriching solution for B. typhosus (Hoffmann and Fischer) . 

 — To peptone-meat-broth add i per cent, nutrose, 0.5 per 

 cent, caffein, and i per cent, solution of crystal violet. 



Endo's medium. — 



Nutrient agar (3JS) 1000 c.c. 



Lactose 10 g- 



Alcoholic solution of fuchsin j c.c. 



Sodium sulphite (10^ solution) 25 c.c. 



Sodium hydrate (10^ solution) 10 c.c. 



Drigalski and Conradi's medium (Modified by Harris). — 



Dextrose-free broth 2000 c.c. 



Nutrose . . ' 20 g- 



Agar 40 g. 



Boil, dissolve, neutralize to phenolphthalein, autoclav at 120° 

 for 5 minutes. Clarify with whites of four eggs and filter. Then 

 add — 



