This was a suit by a father against his son, on a promissory note payable in a stated sum of money, to wit, $600. The defendant filed a plea setting forth that it was agreed at the time the note was executed that it was not to be paid in money, but by the father’s boarding it out. The plea set forth that the note had been paid according to such understanding and agreement by three-years board furnished by the son to 'the father. In response to a demurrer, the defendant, amended his plea by setting up that at the end of each month during the period in which board was furnished, the plaintiff ratified the original oral agreement to the effect that $16.67 per month should be applied on the note. It was further set forth by the amendment that at the expiration of the tliree-year period the plaintiff and the defendant entered into a contract with reference to the satisfaction of the note, by which it was agreed that the note had been paid in full except the last year’s interest, which was then unpaid, and which], it was alleged, was subsequently paid by the furnishing of additional board. The first amendment was not sustained by any sort of testimony. The evidence with reference to the last-mentioned amendment, while in dispute, authorized a finding for the defendant, who testified as follows: “At the end of the three years my father said that I had taken care of him for three years and the note was paid. As to what was said about the thirty dollars due as interest, we agreed that he could stay on as long as he wanted to, and the thirty dollars was to be paid in that way. My father stayed there about eight months after that last agreement. The eight month's that he stayed there was worth the interest that was due.” The jury found in favor of the defendant, and the plaintiff excepts to the order overruling his motion for a new trial.
*261. The rule is well settled that where a question as to the sufficiency of the pleadings has been raised by demurrer, and the pleader seeks to conform to an adverse ruling by amending them so as to meet the objection and prevent a dismissal, he will not thereafter be heard to complain that the antecedent ruling to which he has thus submitted was erroneous, or that the amendment was unnecessary. McConnell v. Frank E. Block Co., 26 Ga. App. 550 (106 S. E. 617). Moreover, it is the law that, while as between the original parties the consideration of a note is ordinarily open to inquiry, the rule which prevents the alteration of a written agreement by proof of a prior or contemporaneous agreement in parol does not permit, under the guise of inquiring into the consideration, a change of the terms of a written instrument as actually expressed, such as that the sum agreed to be paid in money was not in fact to be thus paid. Boynton v. Twitty, 53 Ga. 215; Byrd v. Marietta Fertilizer Co., 127 Ga. 30 (56 S. E. 86); Hirsch v. Oliver, 91 Ga. 554 (18 S. E. 354); Rheney v. Anderson, 22 Ga. App. 417, 418 (96 S. E. 217). Accordingly, the defendant was not only bound by submitting to the ruling which sustained the demurrer and amending his cross-action in accordance therewith, but the ruling was in accordance with law.
2. There is another principle of law, invoked by the plaintiff, to the effect that a plaintiff must recover upon the cause of action as laid. This rule would apply to a defendant who seeks to recover by way of set-off or counterclaim, and would prevent him from sustaining a claim based by the pleadings upon an expressed contract by evidence setting up an implied obligation by way of quantum meruit. Shropshire v. Heard, 27 Ga. App. 256 (107 S. E. 892); Seaboard Air-Line Ry. Co. v. Henderson Lumber Co., 28 Ga. App. 391 (111 S. E. 220). This principle, however, does not apply in the plaintiff’s favor in the instant case, since the amendment setting up the plea of complete satisfaction of the note by virtue of the contract and agreement made subsequent to its execution, although styled by the defendant as a plea of set-off, is in fact by its terms a plea of satisfaction and extinguishment of the debt; and even if it could be treated as a plea of set-off, according to its own nomenclature, it was not based upon an implied obligation, but set forth an expressed agreement and understanding with reference to' the satisfaction of the written obligation. If the father and son entered *27into the agreement set forth by the amendment, it must be enforced, irrespective of the actual merits of the son’s claim which afforded the basis of such an agreement. Dickerson v. Dickerson, 19 Ga. App. 269 (91 S. E. 346). Accordingly, the sole question in the instant case was whether or not the son, under the testimony, had established to the satisfaction of the jury the making of the agreement in,satisfaction of the note, as set forth by the amendment.
3. The sole issue between the parties, as to whether the agreement set forth by the amendment had been entered into, being in sharp dispute under the evidence, it might have been misleading to the jury and harmful to the plaintiff for the court to instruct them in effect that while ordinarily there would be no implied obligation on the part of the father to pay for the services rendered by the son, “there may be cases where the law will imply a contract where the parent is to pay the child for the services rendered by the child to the parent.” In other words, the jury might, under this instruction, have believed the testimony of the father denying the agreement set up by the amendment, but might nevertheless have felt that in view of all the testimony and the evidence as to surrounding facts and circumstances, there was an implied obligation of the father to pay for the services rendered, irrespective of any expressed understanding as set forth by the amendment, and upon which the defendant’s right to prevail was solely dependent. Accordingly, the court, erred in overruling the motion for a new trial.
Judgment reversed.
Stephens and Bell, JJ., concur.