Gram positive bacteria retain the crystal violet and Iodine complex and are stained blue, whilst Gram negative bacteria are counterstained red. The teaching notes have been designed for the teacher with little experience in handling micro-organisms and include step by step diagrams of the practical procedure and the whole experiment can be done in one lesson.

The accompanying booklet entitled 'Safe Handling of Micro-organisms' includes full instructions on safety, aseptic technique, culturing and disposal.

The Gram Stain Kit contains:

• Escherichia coli culture
• Staphylococcus albus culture
• Crystal Violet stain 25ml
• Grams Iodine stain 25 ml
• Phenol-Fuschin stain 25ml
• Dropping bottles for alcohol
• Full teaching notes

In addition, the following equipment is required:

• Distilled water
• Inoculating loop
• Alcohol
• Glass microscope slides
• Filter paper
• Forceps
• Bunsen burner
• A microscope fitted with a x100 oil immersion objective to view the prepared slide