120 MORPHOLOGY AND LIFE HISTORY 



clean cover-glass; invert the cover-glass and lay 

 it upon the pins so the drop will be in the center of 

 the glass. Place the slide on the stage of the 

 microscope. Focus with great care, so as not to 

 break the fragile cover-glass or wet the objective. 

 The bacteria should be just visible with the low 

 power; with the high power you should be able to 

 make satisfactory studies. 



3. Observe the bacteria in the mount. Note variations 

 in shape: the spherical or coccus forms, the rods or 

 bacillus forms, and, usually in such material, curved 

 or spirillum forms. Note also the rapidity and char- 

 acter of the motion. Do they all move? Some 

 have a vibratory motion; others move forward in a 

 direct line. 



4. The technique of staining is too difficult for the 

 beginner in botany. The instructor will furnish 

 stained and mounted bacteria for examination with 

 the high power. In some instances the instructor 

 may use the oil immersion if it seems advisable. 

 The following types are suggested for this study: 

 Bacillus subtilis (hay bacillus). 



Bacillus proteus (decay), stained to show flagella. 

 Bacillus tuberculosis. 

 A Streptococcus and a Spirillum. 

 In your notes enter data on (a) comparative size, 

 (b) absorption of stain by bacteria, (c) grouping, 

 (d) source. 

 D. Naked-eye Characters: 



i. Prepare agar-agar culture medium, or use prepared 

 medium supplied in a test-tube by the instructor. 

 Melt the agar carefully over an alcohol or Bunsen 

 flame, beginning at the top. (Why begin at the top?) 

 When it is melted pour the agar into a sterile Petri 



