I30 LABORATORY GUIDE IN BACTERIOLOGY 



1. Routine study. — In addition to the usual media, 

 inoculate an extra tube of Dunham's pepton solution 

 from each organism. Observe from day to day the 

 action of these two organisms on gelatin, and compare 

 the results by tabulation. Observe the formation of 

 coccoid involution forms on agar after 3 days. Also 

 make plates in gelatin, observe the colonies from day 

 to day, and compare. 



2. Special study. — ^Test for the nitroso-indol or 

 cholera-red reaction. (See test for indol, p. 114.) 

 Make two tests, using one of the cultures in Dunham's 

 solution after 24 hours, the other after 6 days. Com- 

 pare the results of these two tests. 



3. Special study. — Stain for flagella by Loffler's 

 method (see p. 117). 



4. Special study. — Schottelius' enriching method, 

 designed to demonstrate the presence of spirilla in 

 water. 



a) Prepare a solution of 2 grams Witte's pepton and 

 o . 5 gram sodium chlorld in 100 c.c. of water. 



b) Distribute in three small Erlenmeyer flasks, and 

 sterilize in the autoclave. 



c) Inoculate one of these flasks with Sp. metch- 

 nikovii and B. suipestifer or any other motile bacillus. 



d) Incubate at 37° C. for 18-24 hours. 



e) After that time, take one loopful from the surface, 

 inoculate the second flask, and incubate as before. 

 Also make a stained preparation from the siu:face of 

 the solution. 



/) After 18-24 hours, make a stained preparation 

 from the surface of the second flask, and examine for 

 spirilla. 



