509. Securities must be in existence at time of consolidation.

Both the securities which the mortgagee claims to consolidate must be in existence at the time when the claim is made1. There is no right to apply a surplus on an existing mortgage to make good a debt secured by a mortgage which has ceased to exist by reason of the determination of its subject matter, such as a life interest2 or a lease3. In such a case, the debt formerly secured by the mortgage has ceased to be a secured debt, and a mortgagee who has in his hands a surplus from a realised security may not, as