Newcomer Supply Gram, Multi-Tissue, Artificial Control Slides are for the positive histochemical staining of gram positive and gram negative bacteria in separate tissue sections. Escherichia coli and Staphylococcus aureus are used to produce the positive controls. Gram, Multi-Tissue, Artificial Control Slides contain sections of Gram positive staining rat lung, Gram negative staining rat lung and negative staining human lung.