44 



GENERAL BACTERIOLOGY 



d. Examine the thinner layers, noticing the arrangement of cells 

 with reference to each other, and draw a sufficient number to illus- 

 trate this relationship. 



HANGING-DROP PREPARATIONS. 



a. Make hanging-drop preparations from bouillon cultures pre- 

 pared above (22) and also from those supplied. 



&. Examine with oil-immersion objective and assign organisms 

 to their proper places, as determined by cell grouping, in the follow- 

 ing scheme : 



AGAR HANGING-DROP CULTURES (Wesbrook). 

 a. Melt a tube of agar and cool to 43 C. 



Z>. Sterilize a cover-glass by passing it two or three times through 

 the flame quickly. 



c. With the needle make a streak on the cover glass about 3 mm. 

 long of B. subtilis. 



