26 CULTURE MEDIA. 



in each test-tube, or put in quantities of 50 or 100 c.c. in small Erlen- 

 meyer flasks. It is then sterilized in the autoclave (10 pounds for 15 

 minutes) or in the Arnold. 



For Conradi-Drigalski Medium. Melt down the lactose litmus 

 agar in the flasks holding 100 c.c. Then add to the 100 c.c. of medium, 

 i c.c. of a solution of crystal violet (crystal violet o.i gram, distilled water 

 100 c.c.). The medium is then ready to put into plates. Colon 

 colonies are pink. Typhoid and dysentery colonies, a bluish-gray. 



