USE OF WASHED AGAR IN CULTURE MEDIA 



591 



TABLE 1— Continued 



STANDARD EXTRACT AGAR 



STANDARD INGREDIENTS AND 

 WASHED AGAR 



INCREASE OVER STANDARD 

 EXTRACT AGAR 



Pasteurized milk — continued 



The washed agar used in these experiments was prepared as 

 follows : For 1 liter of double strength (3 per cent) agar, 30 grams 

 of shred agar was placed in a flask with 2000 cc. of distilled water. 

 This was allowed to stand for 24 hours at room temperature. 

 At the end of this period as much water as possible was poured 

 off, a piece of cheesecloth being placed over the top of the flask. 

 Fresh distilled water was added to make up for the water poured 

 off. The agar was allowed to soak another twenty-four hours, 

 after which it was thrown on to a cotton-flannel cloth in a funnel 

 and washed once with 1 liter of distilled water. The agar was 

 allowed to drain and as much as possible of the remaining water 

 was pressed out by squeezing the filter cloth with the hands. 

 A container large enough to hold the agar was counterpoised on 

 the laboratory scales, and the agar was placed in it. In the 

 opposite pan was placed 30 grams for the weight of the agar 

 and 1000 grams for the weight of the water in which it was to 

 be dissolved. Then water enough was added to the agar to 

 make up this weight, it was then dissolved and filtered. 



