right of contribution where each surety is severally bound for a given portion only of the guaranteed debt; nor in the case of a surety for a surety; nor where a person becomes a surety jointly with another and at the latter's request. Contribution may be enforced, either before payment, or as soon as the surety has paid more than his share of the common debt; and the amount recoverable is now always regulated by the number of solvent sureties, though formerly this rule only prevailed in equity. In the event of the bankruptcy of a surety, proof can be made against his estate by a co-surety for any excess over the latter's contributive share. The right of contribution is not the only right possessed by co-sureties against each other, but they are also entitled to the benefit of all securities which have been taken by any one of them as an indemnity against the liability incurred for the principal debtor. The Roman law did not recognize the right of contribution among sureties. It is, however, sanctioned by many existing codes. Discharge of liability The most prolific ground of discharge of a guarantor usually arises from the creditor's conduct. The governing principle is that if the creditor violates any rights which the surety possessed when he entered into the suretyship, even though the damage is only nominal, the guarantee cannot be enforced. The surety's discharge may be accomplished (1) by a variation of the terms of the contract between the creditor and the principal debtor, or of that between the creditor and the surety; (2) by the creditor taking a new security from the principal debtor in lieu of the original one; (3) by the creditor discharging the principal debtor from liability; (4) by the creditor binding himself to give time to the principal debtor for payment of the guaranteed debt; or (5) by loss of securities received by the creditor in respect of the guaranteed debt. The first four of these acts are collectively termed a novation. In general whatever extinguishes the principal obligation necessarily determines that of the surety, not only in England but elsewhere. By most civil codes the surety is discharged by conduct of the creditor inconsistent with the surety's rights, although the rule prevailing in England, Scotland, America and India which releases the surety from liability when the creditor extends without the surety's consent the