CULTURE MEDIA 21 



Dilute 1 part of the above medium with 2 parts of tap water 

 and add 0.01 per cent of ferric chloride (FeCl3'6H20). 



Medium 43 



Sodium Nitrate Solution (Bristol's) ^ 



Monopotassium phosphate (KH2PO4) 0.5 gm. 



Sodium nitrate (NaNOs) 0.5 gm. 



Magnesium sulphate (MgS04-7H20) . 15 gm. 



Calcium chloride (CaCl.) 0.05 gm. 



Sodium chloride (NaCl) 0.05 gm. 



Ferric chloride (FeCh-OH.O) . 01 gm. 



Water 1,000.0 cc. 



1 Bristol, B. M., Ann. Bot., 34: 35-79, 1920. 



Because of the special sensitiveness of the algae to copper, 

 it is well to avoid distilled water unless from glass. 



MEDIA FOR UREA BACTERIA 



Medium 44 



Urea Citrate Solution^ 



Urea (CO(NH2)2) 30.0 gm. 



Dipotassium phosphate (K2HPO4) 0.5 gm. 



Calcium citrate (Ca3(C6H507)2-4H20) . . . 10.0 gm. 



Tap water 1,000 :0 gm. 



2S0HNGEN, N. G., Centr. Bakt. II Abt., 23: 91-98, 1909. 



Reaction about pH 7.2. 



Medium 45 



Urea Solution ^ 



Urea .^ 20.0 gm. 



Dipotassium phosphate (K2HPO4) 1-0 gm. 



Calcium chloride (CaClo) 0.1 gm. 



Magnesium sulphate (MgS04-7H20) 0.3 gm. 



Sodium chloride (NaCl) 0.1 gm. 



Ferric chloride (FeCla-OHaO) 0.01 gm. 



Beef extract 5.0 gm. 



Tap water 1,000 . cc. 



3 Viehoever, A., Centr. Bakt, II Abt., 39: 209-359, 1913. 



