The Cell Wall and the Gram Reaction

The factor or factors upon which the Gram reaction depends have never been satisfactorily determined. Whether the reaction is due to protoplasmic or cell wall differences is a disputed ques-tion. Important recent contributions dealing with explanations of the Gram reaction favor the view that the reaction is deter-mined by the protoplasm and that the cell wall is a negligible factor. Stearn and Stearn assume that the chemical nature of the bacterial protein is the determining factor and present some inter-esting experiments to support their theory that the Gram reaction depends upon the isoelectric point and the pH (Stearn and Stearn, 1923, 1924, 1925, 1928a, 1928b). In attempting to correlate reduction in size in dye exposed anthrax cells with loss of Gram positiveness, Churchman (1927) presents the ingenious theory that the cell consists of an outer layer which is Gram-positive and an inner layer which is Gram-negative. According to this theory, destruction or loss of the outer layer results in the cell becoming Gram-negative. No explanation is offered as to why the outer layer of protoplasm is Gram-positive and the inner layer or medulla Gram-negative. The strongest evidence in favor of the cell wall as the deter-mining factor in the Gram reaction has been presented by Benians (1912, 1920). His work suggests that the Gram reaction is determined by the physical structure of the cell wall. He ex-cludes the cell protoplasm or its chemical nature as factors in any way affecting the Gram reaction. The experiments described in the present paper were designed to discover whether the Gram reaction depends upon the cell protoplasm, the cell wall, or both. No attempt was made to