Consider an mommy in which the young are each endowed with 3; units of the con- sumption good? while the old have at money. The stock of money.r is always the same? so that Mg = M for all t. Each generation gradually changes its consumption, so that c1; = {1 "fly, 1where ll s: 'r d: l. The population is always the same, so that Nt = N. for all t