THE PREPARATION OF GELATIN AND AGAR 13 



stirring to prevent scorching, until the agar is dissolved, giv- 

 ing a thick, homogeneous, pasty substance. Pour 300 cc. of 

 bouillon ( 11) from a flask into the cup containing the dis- 

 solved agar. Place the dish containing the mixed agar and 

 bouillon in a closed water bath and boil for 20 minutes, then 

 cool it to a temperature between 45 and 50 C., add the 

 white of one egg, and thoroughly mix in the liquid agar. 

 This is easily accomplished by pouring it a number of times 

 from one beaker to another. When the egg albumen is dis- 

 solved the agar is returned to the water bath and boiled vig- 

 orously until the white of the egg is firmly coagulated. This 

 usually takes about 20 minutes. Filter the agar immediately, 

 while hot, through ordinary filter paper which has been mois- 

 tened with boiling water. Distribute the filtrate in small and 

 large tubes, as directed. Sterilize, label, and store the agar in 

 the same manner as the gelatin. 



