Gram Stain Kit is used to identify two distinct groups of microorganisms in tissue sections on Artisan Link and Artisan Link Pro Staining Systems. Those that retain primary dye (Crystal Violet) are called Gram-positive. Those that lose the primary dye during decolorization are called Gram-negative. Mechanisms of Gram-positive organisms retaining the primary stain and Gram-negative organisms losing the primary stain are the result of the chemistry and structure of the organism's cell walls. The tissue elements are stained as follow: Gram-positive organisms: blue, Gram-negative organisms: red and background: varying shades of blue/green.