Gram Yellow Stain Kit is intended to identify Gram-positive and Gram-negative microorganisms in tissue sections on the Artisan Link and Artisan Link Pro Staining Systems. Gram Yellow Stain Kit is used to identify two distinct groups of microorganisms in tissue sections. 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. Gram-positive organisms: dark blue, Gram-negative organisms: light pink to magenta and the background: yellow.