Papinianus, Questions, Book LVII. Where a surety kills an animal which had been promised before the principal was in default in its delivery; Neratius Priscus and Julianus hold that an action on the ground of fraud ought to be brought against him; since the debtor having been discharged, he himself, in consequence, is released from liability.

Papinianus, Questions, Book XXXVII. A debtor is entitled to an action under the Lex Aquilia where a party who stipulated for delivery, and before default of the debtor, wounds the animal which was promised; and the same rule applies if he should kill it. But where the party who stipulated kills the animal after the default of the promisor, the debtor will undoubtedly be discharged; but in this instance he will not have a right to institute proceedings under the Lex Aquilia, since the creditor must be held rather to have injured himself rather than another.

The Same, Questions, Book XXXVII. Where a father, ignorant that his daughter has been divorced, pays the dowry to her husband in compliance with his promise, the money can be recovered, not by the action for the payment of what was not due, but by the action on dowry.

The Same, Questions, Book XXXVII. Where a slave undertakes the execution of an implied trust under the direction of his master, it has been decided that, because he was obliged to obey his master, he will be entitled to the benefit of the Falcidian Law.

The Same, Questions, Book XXXVII. If I stipulate as follows, “Do you promise to pay this sum of a hundred aurei?” although the clause, “Provided there are a hundred aurei,” is understood, this addition does not establish a condition, for if there are not a hundred aurei, the stipulation is void; and it has been decided that a clause which does not refer to the future, but to the present time, is not conditional, even though the contracting parties may be ignorant of the truth of the matter.

Ad Dig. 45,2,10ROHGE, Bd. 12 (1874), Nr. 81, S. 253: Compensationsbefugniß eines vom Gläubiger wegen einer Correalschuld in Anspruch genommenen Schuldners mit Privatforderungen des andern Socius.The Same, Questions, Book XXXVII. If two joint-promisors are not partners, the fact that the stipulator owes a sum of money to one of them will be of no advantage to the other.

The Same, Questions, Book XXXVII. A creditor, who became the heir to a portion of the estate of his debtor, accepted his co-heir as surety. So far as his own share of the estate is concerned, the obligation is extinguished by merger or (more correctly speaking) by the power of payment. But, with reference to the share of the co-heir, the obligation remains unimpaired, that is to say, not the obligation of his suretyship but the hereditary obligation, since the larger one has rendered the smaller of no force or effect.