accretes to its final mass depends on its initial mass ratio and on the properties of the molecular cloud core from which it formed.

As examples, we give the evolution of ‘seed’ binaries that form from two types of molecular cloud core. A greater range of molecular cloud cores is considered in [@Bate2000]. Figure \[bate.uniform\] presents the evolution of binaries formed from molecular cloud cores which had uniform-density and were in solid-body rotation before they began to collapse dynamically. In Figure \[bate.1r\], the molecular cloud cores had radial density profiles of $\rho \propto 1/r$ with solid-body rotation, initially. Evolutionary curves are provided for ‘seed’ binaries with initial mass ratios ranging from $q=0.1-1.0$.

In all cases, the long-term evolution is towards a mass ratio of unity, since the material that falls in later has higher specific angular momentum relative to that of the binary. Thus, the more the binary accretes relative to its initial mass, the stronger the tendency is for the mass ratio to be driven to unity. Similarly, the more the binary accretes relative to its initial mass, the more likely it is to be surrounded by a circumbinary disc. Note that, in the previous sections, we found that 