The aim of the last two chapters was to define the natural equilibrium dynamics of the Ricardian one-sector and two-sector models and to study the disequilibrium paths originating in the failure of one of the initial ('stock') conditions to meet the requirements for the system to start off and move along the natural equilibrium path. Attention will now be addressed to a different type of departure from the equilibrium path - that originating in the change in one of the parameters defining the natural equilibrium growth rate ('flow' conditions) (Hicks (35), ch. 8). As mentioned in Chapter 1, this type of problem - that Hicks ((35), ch. 16) has called 'traverse' - may be studied under the heading of 'disequilibrium dynamics'.