Difference between the provisions of Sections 18 and 19.

NATARAJAN, J.:- The plaintiff in O.S. No.37 of 1971 on the file of the court of the Subordinate Judge of Devakottai is the appellant. He filed the suit in forma pauperis for recovery of moneys due under a mortgage created by deposit of title deeds by the first defendant on 9-9-1946 in favour of the plaintiff's father, one Lakshmanan Chettiar. The case of the plaintiff was to the following effect: Defendants 1, 15 and 16 are brothers and were members of a joint Hindu family. A sum of Rs. 18000 belonging to the joint family of the plaintiff and his father was deposited with the first defendant for earning interest. The deposit was made in the name of the plaintiff's mother, one Paripoorna Achi. When the plaintiff's father demanded repayment of the amount in Madras and insisted on furnishing of security in the event of non-payment, the first defendant executed a fresh deposit letter in favour of the plaintiff's father on 9-9-1946 for a sum of Rupees 20,000. The said letter was executed at Madras and on 10-9-1946 the first defendant delivered the title deeds pertaining to two items of properties, described as Items 1 and 2 in the plaint II with intent to create a security. Thus an equitable mortgage by way of collateral security was made in favour of the plaintiff's father and the mortgage was still subsisting. Between the period 3-9-1949 and 26-2-1958, the first defendant had paid certain sums of money amounting in all to Rs. 1000 on several occasions towards the equitable mortgage. The plaintiff's father died on 22-6-1963, leaving as his heirs his son (the plaintiff), his widow Paripoorna Achi and a daughter by name Deivanai, Achi. The plaintiff's mother and sister had released their shares in the mortgage amount in favour of the plaintiff by means of a registered release deed dated 21-2-1968. Defendants 2 and 3, knowing fully well the existence of the equitable mortgage, purchased the one-third share of the first defendant in item 1 of schedule II property on 3-3-1958 in E.P. 81 of 1957 in O.S. 74 of 1950 on the file of the Sub Court. Devakottai. Likewise, one Ramaswami Chettiar, who is the father of defendants 4 to 13, and the husband of the 14th defendant, purchased, with full knowledge of the equitable mortgage, the undivided onethird share of the first defendant in Item 2 of schedule II on 9-12-1963 in E. P. No. 22 of 1962 in O.S. 4 of 1949 on the file of the Sub Court, Devakottai. The respective court auction-purchasers, having purchased the equity of redemption with knowledge of the subsistence of the mortgage, are legally bound to discharge the mortgage debt secured by the equitable mortgage. After the court auction sale in their favour, defendants 2 and 3, in collusion with the mortgagor (first defendant) and his brothers, defendants 15 and 16, filed a suit O.S. No. 50 of 1969 on the file of the Sub Court, Devakottai, for partition of the properties belonging to the joint family of defendants 1, 15 and 16, and obtained a fraudulent partition decree under which a small extent of property of meagre value was allotted to the share of the first defendant. Such a decree had been collusively obtained in order to defeat the plaintiff from realising the mortgage debt. Apart from the fraudulent nature of the suit, it is also bad in law for partial partition. The plaintiff made repeated demands on the first defendant and the court auction-purchasers of the one-third share in the mortgaged properties to pay the mortgage amount together with interest etc. but they proved of no avail. The fourth defendant died during the pendency of the suit and hence his legal representatives, defendants 17 to 21, were brought on record. Since defendants 2 and 3 as well as defendants 5 to 14 and 17 to 21, have purchased the one-third share of the first defendant with full knowledge of the subsistence of the mortgage, they are bound in law to discharge the mortgage debt. Except the properties mentioned in the plaint, defendants 1, 15 and 16