Laboratory Directions for Beginners in Bacteriology

isfactorily by washing them in hot soap-suds, rinsing them in water, and wiping them with a soft cloth. (f) Cleaning used culture apparatus. Place the tubes, flasks, or Petri dishes containing old cultures in a water bath, cover them with water, add a little sal soda (about an ounce to the gallon of water), and boil for 20 minutes. Pour off the water and empty the tubes, after which again boil them for 5 minutes in clean soap and water. Then wash and treat with the cleaning mixture the same as the new tubes. Cultures of spore-bearing pathogenic bacteria, such as those of anthrax, should be destroyed by heating in the autoclave at a temperature of at least 110 C. for half an hour before the tubes are emptied and washed. 4. A Method fpr Cleaning Cover-glasses for Flagella Stain. ? For this work the ordinary method of cleaning cover-glasses is not sufficient, although the heating will often give a perfectly satisfactory cover-glass. The following treatment was highly recommended to me by Dr. Erwin F. Smith. First clean the cover-glasses by the ordinary method, after which boil them in an agate cup or glass beaker in a 10% solution of caustic soda for 5 minutes. After cooling, rinse the cover-glasses thoroughly in distilled water, place them in a beaker and cover them with a i % solution of hydrochloric acid, heat to the boiling point, and allow to stand for several hours (over night or longer). Then pour the acid off and rinse the cover- glasses several times in d...