UREA GELATIN 99 



1. Heat in the steamer or over a free flame until the 

 precipitate settles. 



2. Filter and sterilize. 



3. In order to diminish the loss of ammonia from urea 

 the culture-media should be sterilized in the steamer 

 twenty minutes on three successive days. 



Medium 20 

 Urea Solution 



Certain forms of urea fermenters prefer a medium richer 

 in urea. This may be prepared by adding 10 per cent, of 

 urea to the bouillon. 



Medium 21 



Urea Solution 



Urea (CO(NH 2 ) 2 ) 30.0 gm. 



Dibasic potassium phosphate (K2HPO4). 0.5 gm. 



Calcium citrate (Ca3(C6H 5 O 7 )2 + 4H 2 O) 10.0 gm. 



Tap-water 1000.0 c.c. 



Sohngen, N. L., Centbl. Bakt. (etc.), Abt. 2, Bd. 23, p. 94, 1909. 



Medium 22 



Urea Solution 



Urea (CO(NH 2 ) 2 ) 50.0 gm. 



Dibasic potassium phosphate (K 2 HPO 4 ) 0.5 gm. 



Soil extract 100.0 c.c. 



Tap-water 900.0 c.c. 



Lohnis, F., Centbl. Bakt. (etc.), Abt. 2, Bd. 14, p. 714, 1905. 



Medium 23 

 Urea Gelatin 



Gelatin 120 to 150 gm. 



Urea (CO(NH 2 ) 2 ) 20 c.c. 



Bouillon ( i.o) 1000 c.c. 



