Time point of 1stmetastasis formation for the MS- and GDR-model. Time of 1st metastasis formation as a function of maximal tumour size b of the Gompertz function. Results for the MS-model are shown in the upper, those for the GDR-model in the lower part. The simulations were calculated for three different rate parameters μ, which corresponded to an initial doubling time of 5, 10 and 20 days at a reference cell size of 1011, respectively. The rates for metastasis formation were chosen the same as in Figures 2, 3 (black symbols) or reduced by one tenths (red symbols). Dissemination occurred proportional to V (MS-model) and V2/3 (GDR-model). For the blue graphs a reduced dissemination (V2/3 and V1/3) was expected.