44 



the organisms in each. Indicate the morphologic characters 

 by which each genus can be differentiated from the others. 



Make a cover-glass preparation from each culture and 

 stain with an aqueous solution of Methyl-violet. Make a 

 careful microscopic examination of each preparation and 

 describe the bacteria in each. 



Make careful notes on the appearance of the bacteria in 

 each preparation and preserve one specimen of each to ac- 

 company notes. 



Measure carefully with the filar micrometer the length 

 and thickness of three individual bacteria in the stained 

 preparation of the bacillus. Record the measurements in 

 microns. (For the use of the micrometer see chapter 

 on magnification and micrometry in "The Microscope" 

 by Professor S. H. Gage.) 



Inoculate a tube of agar and one of gelatin from each of 

 the bouillon cultures. 



EXERCISE XVI. 



STUDYING THE MORPHOLOGY OF BACTERIA. 



65. General directions. Examine and describe the 

 cultures made in Exercise XV. 



Examine in the fresh condition and in stained cover-glass 

 preparations the bacteria from the agar cultures and make 

 careful notes on their forms. Stain with alkaline methylene- 

 blue and carbol fuchsin. Measure a few of the individual 

 bacteria in the preparations of the micrococcus, and strep- 

 tococcus. 



Inoculate a tube of agar, one of gelatin and one of 

 bouillon with Bacillus subtilis from a culture furnished and 

 place the inoculated tubes in the incubator. 



