Mass distribution averaged over the indicated intervals of age for the Antennae clusters (data points) and for Model 2 with k = 0 (lines). In this model, clusters have a power-law initial mass function, a constant formation rate, and gradual mass-dependent disruption. The solid lines were computed for the older clusters only from Equations (B9) and (B10) with the indicated values of τ _*. The dashed line, with τ _* = 1.4 × 10 ⁷ yr, provides a good fit to the observed distribution for the older clusters.