Evolution of the normalized primary-mass distribution under sustained gas accretion. The initial population consists of a Salpeter-like power law combined with a Gaussian component centered at μ = 10 M_⊙, with masses drawn between 5 and 50 M_⊙. The gas density evolves as ﹩{\rho }_{g}(t)=7\times 1{0}^{-16}\exp (-t/{\tau }_{{\rm{gas}}})\,{\rm{g}}\,{{\rm{cm}}}^{-3}﹩ with τ_gas = 10 Myr. Different colors show the mass function at successive times. Solid curves correspond to Monte Carlo calculations and dashed curves to the analytical solutions derived using the continuity-equation framework. The distribution broadens and extends toward higher masses as accretion drives objects through mass space at mass-dependent rates.