Procedures are described for showing the effectiveness of antibiotics (penicillin, ampicillin, and tetracycline) against a nonpathogenic bacteria strain (Bacillus cereus). Methods are outlined for preparing nutrient agar, sterilizing tubes, pouring agar plates, preparing antibiotic discs, and transferring antibiotic discs to agar plates. (CS)

Describes a biochemistry experiment that illustrates the methodology of affinity chromatography by attaching avidin, a glycoprotein in egg white, to a Sepharose matrix in order to bind biotin-containing proteins. (MLH)

Discusses the technique of producing a grating with a spacing of 1 micron and 5 slits 50 microns long and 0.3 micron wide. Indicates that the slits are suitable for use in examination of electron diffraction patterns in the Gedanken experiment. (CC)

Discusses the structure and formation of snow crystals, outlines the history of snow removal, and describes techniques that can be used by students for studying snowflakes and relating their structure to the conditions under which they were formed. (JR)

Discusses concerns relating to the preparation of internal and external practical examinations in microbiology at the university degree or diploma level. Outlines the basic objectives, initial organization, and major considerations in preparing the laboratory examination. (JR)

Discusses an experiment which illustrates the non-mixing properties of water at normal temperature with oil because of water's strong, open-ended hydrogen bonding interactions. Examples of the mixing properties between non-interacting substances and the near-complete mixing between water and solvents with limited H-bonding capacity are also given.…