25 



the bodies of the bacteria. If present they can usually be 

 seen in both positions. Is there any evidence of a capsule 

 around the bacteria ? 



EXERCISE VII. 



MAKING AND STAINING COVER- GLASS PREPARATIONS, 

 AND FORMULAE FOR STAINING SOLUTIONS. 



§ 27. General Directions. Make two cover-glass prepa- 

 rations from each of the cultures made in Exercise V and stain 

 one with alkaline methylene-blue and the other with carbol 

 fuchsin. Describe the appearance of the bacteria and make 

 a drawing of a few individual bacteria from the preparations 

 made from the agar culture. 



Preserve a cover-glass preparation mounted in balsam and 

 labeled to accompany notes. 



Prepare the staining fluids used in this exercise from the 

 formulae given. 



Read the paragraphs in the text-books on making and 

 staining cover-glass preparations. 



§ 28. Making cover-glass preparations, (i) From 

 bouillon cultures. Place 2 clean cover-glasses on the tray. 

 With the loop remove a drop of the bouillon culture and 

 spread it in a thin layer over about yz of the surface of the 

 cover-glasses. One loopful will ordinarily make from 2 to 4 

 preparations. Allow the liquid to dry on the cover-glasses 

 in the air. When dry fix the bacteria to the cover-glasses 

 by passing them, film upward, 3 times through the middle 

 of the upper half of the gas flame. Each passage (complete 

 circle) should not occupy more than one second. After fix- 

 ing they are ready for staining (§ 29). (2) From cultures 

 on .solid media (agar, gelatin, potato, serum, etc.). Place 

 the cover-glasses on the tray and on the center of each a 



