NITRIFICATION IN SOLUTION 



249 



cellulose-decomposing organisms probably play a most 

 important part? How is this determined? 



9. What types of anaerobic cellulose-decomposing bac- 

 teria are favored by this synthetic medium? These bac- 

 teria have only in exceptional cases been grown on solid 

 media. How can these types be separated? 



10. Data and observations should be given in full. 

 Draw any conclusions warranted and indicate any practical 

 applications that may be made, 



REFERENCES 



LOHNIS: Laboratory Methods in Agricultural Bacteriology, p. 93. 

 LIPMAN and BROWN: Laboratory Guide in Soil Bacteriology, p. 64. 

 MARSHALL: Microbiology, pp. 246-248. 

 McBETH and SCALES: I.e., Exercise IV. 



EXERCISE 6. TO ILLUSTRATE NITRIFICATION IN 

 SOLUTION 



Apparatus. Nine 50 c.c. Erlenmeyer flasks; 75 c.c. 

 each of Solutions I, II and III for nitrification (see appen- 

 dix); Nessler's solution; a-naphthylamin; sulphanilic acid; 

 2% diphenylamin in sulphuric acid; aqueous alcoholic 

 stains. 



Cultures. Rich soil from cultivated land; manure 

 from surface layers of manure heap. 



Method. 1. Place 25 c.c. of each solution in a 50 c.c. 

 Erlenmeyer flask and sterilize in the autoclav. 



2. Inoculate as follows: 



and keep at 25 to 30 C., to hasten the action of the micro- 

 organisms. 



