84 LABORATORY BACTKRIOLOGT. 



EXEKCISE XVII. 



ISOLATION OF UREA BACTERIA. 



1. By means of a platinum loop make transfers from 

 flasks 3, J-, 5 and 6 in the preceding experiment into tubes 

 of sterile water. 



2. Prom these dilutions inoculate tubes of sterile lique- 

 fied and cooled (40° C.) "urea agar" in series and plate in 

 the usual way. 



3. Incubate for 3-4 days at 20° C. 



4. Erom several well-isolated colonies inoculate into tubes 

 of "urea solution." 



5. Incul)ate 3-4 days at 20° C. 



6. Test for the production of ammonia by inserting strips 

 of filter paper moistened with Nessler's solution in the upper 

 part of each tube. 



7. Examine the cultures in hanging drop and stained 

 preparations. 



8. Identify by the usual cultural and morphological exam- 

 inations. 



