The properties of an ORN can be investigated by inspecting time courses of the concentrations of chemical substances in it. We can assume an ORN shown in Figure as a possible model of an ORN formed in the above-mentioned pore, in which only chemical substances with meaningful concentrations in the pore are represented, others being neglected. Each circle represents a chemical substance, and different numerals indicate different chemical substances. Thus, a numeral i refers to a chemical substance Ri. A pair of crossed arrows refers to a chemical reaction. Accordingly, Figure shows that R1 and R2 react to produce R7 and R8, and so on. All reactions are assumed to be elementary reactions; thus, their rates can be expressed by second-order rate equations. For example, the rate for the reaction of R1 and R2 to produce R7 and R8 can be expressed as