1899] MICROSCOPICAL JOURNAL. 121 



glasses by passing them, film upward, 3 times through 

 the middle of the upper half of the gas flame. Bach 

 passage (complete circle) should not occupy more than 

 one second. After fixing, they are ready for staining. 

 (2) From cultures on solid media (agar, gelatin, potato, 

 serum, etc). Place the cover-glasses on the tray and on 

 the centre of each a drop of sterile water or bouillon. 

 With the needle, touch the surface growth of the culture 

 and then gently rinse the end of the needle in the liquid 

 on the covers. Spread the liquid on the covers as before. 

 From this point the procedure is the same as that for the 

 preparations made from the bouillon culture. 



Staining Bacteria in Cover-glass Preparations. — (1) 

 With alkaline methylene-blue. With the pipette place a 

 few drops of staining: solution on the film side of the 

 preparation which is either held horizontally with the 

 fine forceps or left resting on the tray. Allow the stain 

 to act for 2 or 3 minutes. Then carefully rinse off the 

 stain in water, holding the cover firmly by one edge with 

 the forceps. After thoroughly rinsing place the prepa- 

 ration, film downward, on a clean slide and dry the up- 

 per surface with a piece of filter paper. It is now ready 

 for the microscopic examination. Use first the dry lens 

 (l-8in. obj.) and then the oil immersion objective. If the 

 specimen is a good one and it is desirable to preserve it 

 wipe off the drop of oil with a piece of lens paper, run a 

 drop of distilled water under the cover-glass which floats 

 it, when it can be easily removed with the forceps. Place 

 it on the tray, film upward, and when dry mount it in 

 alkaline Canada balsam. (2) With carbol-fuchsin. Cover 

 the film on the cover-glass with the stain and allow it to 

 act for about one minute. Then rinse it thoroughly in 

 ^water after which cover it with 1-10 p. c. solution of acetic 

 acid or strong (95 p. c.) alcohol. Allow this to act from 5 to 

 10 seconds and again thoroughly rinse in water and ex- 

 amine as above. (For other decolorizers see textbooks). 



