H.R. Krishnan, J.

This is an appeal by the defendant from the substantially concurrent judgments of the two lower Courts, decreeing the plaintiff's suit for recovery of actual physical possession over a house, on redemption of the usufructuary mortgage created by the plaintiff in favour of the defendant, notwithstanding the fact that at the time the mortgage was created, the defendant was already the lessee of the house from the plaintiff. The questions are, first, whether there was an implied surrender of the lease by the lessee at the time he took the mortgage, either (a) by implication of the terms of the mortgage deed itself, or (b) by operation of law; secondly, looking at it in another way, whether, the lessee's interest merged into the mortgagee-interest, which in its turn could be redeemed without the lease being revived.

The facts are simple and for the most part, admitted, at least at the later stages of the litigation. The plaintiffs are the owners of the house in question about the identity of which there is no dispute. The defendant alleged that he had been a tenant on a monthly basis for a long time. At the first instance, the plaintiffs did not directly admit it, but argued that - even on the assumption that the defendant had been a tenant, it would not affect the plaintiffs' right to get actual physical possession.

But later on, and in this Court particularly, they admit that as a fact, the defendant had been a lessee, till the date of the usufructuary mortgage, on a monthly basis though neither party has brought out what exactly was the rent reserved.

On 18-12-1952, during the pendency of the lease the plaintiffs mortgaged the property with possession for a sum of Rs. 1,725 for two years. Till redemption of the mortgage, the mortgagee was not to pay any rent, and the mortgagor for his part, was not to pay any interest. The following recitals are relevant for our purposes:

I am giving this house in usufructuary mortgage (rehan-bil-kabz) to Motilalji, and I am giving up my possession and putting him in possession of the house........when I redeem this mortgage, I shall take this house back from the possession of the mortgagee........

In other words, the mortgagor gave his possession to the mortgagee on the date of the mortgage and the mortgagee in his turn, agreed to give back the possession after redemption. The crucial point is, whether "possession" in this context was, by intention of the parties or operation of the law, meant actual physical possession or symbolic possession of the reversioner of the lease. In time, the suit for redemption was brought and a preliminary decree obtained. Naturally, the mortgagor was anxious to get physical possession and not merely the lessor's right to reversion, and the mortgagee for his part, wanted the status quo ante to be restored, in other words, the actual possession remaining with him and the symbolic possession going to the lessor-reversioner. Where the house is situated, the Accommodation Control Act is in force and the lessee cannot be ejected except on one of the grounds mentioned in it.

Merger-It is to be remembered that merger as such is essentially different from surrender of any right, though in practice the result might be the same whether the mortgagee has surrendered the lease, or it has merged into the mortgage. The general proposition is that a derivative right automatically merges into the parent right, if the holder of the former happens at any subsequent period to acquire the latter. It will also merge if a person holding the residue of the parent right (or let us say, reversion to the derivative right) acquires the latter. Obvious examples are where the lessee acquires the landlord's reversion, or the landlord holding the reversion acquires the lease, or where the mortgagee acquires the right of redemption or the mortgagor redeems the mortgage. This is because the parent and derivative rights are by their very nature mutually repugnant and incapable