The defendant in error, George G. Carroll, brought this action in the District Court of Sheridan County, against the plaintiff in error, Peter Demple, to recover the sum of one thousand dollars and interest alleged to be due on a certain written agreement. The case was tried to the court without a jury, and judgment rendered against the defendant below (Demple), and he brings error.
The plaintiff, Carroll, alleged in his petition, in substance, that prior' to May 16, 19T1, he was the owner of a large *453interest in, and a large part of the capital stock of the Sheridan Manufacturing Company, a Wyoming corporation, engaged in the business of purchasing wheat from farmers and others and manufacturing it into flour; that on said date he sold his interest and stock in said company to the defendant, Demple, for the consideration of $1,000 cash and the assumption by the defendant of all the obligations incurred by plaintiff for and on behalf of said company, and as evidence of such sale and agreement the defendant executed the following written contract.
“This 16th day of May, 1911, know all men by these presence, that said G. G. Carroll has this day .sold unto Peter Demple his right, title and interest in the Sheridan Manufacturing Company for the sum of (one thousand dollars) $1,000.00 cash. Said Peter Demple agrees to assume all of said G. G. Carroll obligations of the Sheridan Mfg. Co. (Signed) “Peter Demple.”
That one of the obligations incurred by the plaintiff for and in behalf of said company and which was unpaid and owing at the time said contract was made was the sum of $1,000, and interest which had been advanced by plaintiff for said company about December 7, 1908, in payment for wheat sold and delivered to said company by W. S. Metz; which sum the plaintiff borrowed from the First National Bank of Sheridan on his personal note. That defendant had failed and refused to pay said note in accordance with his contract, and that plaintiff was compelled to and did pay said note. Alleged the payment of the $1,000 cash.
The defendant in his answer admitted the purchase of the interest and shares of stock in the company; that he paid plaintiff $1,000, as part of the consideration therefor; and that he signed the instrument set out in the petition. Alleged “that at the time of making the contract and agreement set out in paragraph one of said petition and the purchase by defendant from plaintiff, plaintiff’s interest and stock in said Sheridan Manufacturing Company it was fully agreed, understood and intended by the plaintiff and *454defendant, that, as part of the consideration for such sale, the defendant was to assume and pay certain debts and obligations of plaintiff and the said Sheridan Manufacturing Company, which were at said time specified and agreed upon by the parties, which said specified debts and obligations are as follows, to-wit: one note given to Citizens State Bank of Sheridan, Wyo., in the amount of $1,200.00; one note given to the Bank of Commerce of Sheridan, Wyoming, in the amount of $1,400.00; and small quantities of flour due various persons who had furnished wheat to said Sheridan Manufacturing Company’s mill and were to receive flour in return therefor. That by said agreement in said petition set forth it was agreed, understood and intended by the parties thereto, the plaintiff and defendant herein, that the above debts and obligations were the only debts and obligations to be assumed by said defendant; that the defendant did not at the time of signing said agreement know of the existence of the obligation of plaintiff to the First National Bank of Sheridan, Wyoming, mentioned in said petition, and that defendant did not at said time, or at any time, agree with plaintiff that he, the said defendant, would pay or assume the payment of the said obligation of plaintiff to said First National Bank; that it was fully understood, agreed and intended by the parties to this suit that the full and complete consideration for the sale of plaintiff’s interest and stock in the said Sheridan Manufacturing Company was the sum of, $1,000.00 and the assumption of the specified debts and obligations herein-above set forth.” The other allegations of the petition were denied. A reply was filed denying the new matters set up in the answer.
We have set o'ut at length the allegations of the answer containing what the defendant sought to prove by way of an affirmative defense to the action, in order that the rulings and decision of the court may clearly appear. We think it clearly appears by the answer and the defendant’s evidence that the obligation sued upon was one of the class *455or character of debts and obligations a part of which defendant admits he was to assume and pay as a part of the consideration for the transaction. The answer contains no allegations of any false or fraudulent representations with respect to, or fraudulent concealment of the debts or obligations to be assumed by the defendant, made by the plaintiff to induce, or which did induce the defendant to sign the agreement which he admits in his testimony he read before he signed it. The defendant sought to prove by parol testimony that the contract was different from that contained in the writing. This the court refused to permit, and rightly so under the pleadings. No rule of law is better settled than the one which excludes, as incompetent, parol testimony to vary the terms of a written instrument, or to prove a parol contemporaneous agreement at variance from the writing, in the absence of any allegation of fraud, accident or mistake. On the trial and while the defendant was introducing his evidence, he asked leave to amend his answer and be permitted to plead that defendant’s signature to the agreement was procured by fraud, deceipt, and false representations made by plaintiff. The court refused to permit the amendment to be made, but stated, in substance, that he would permit the defendant, subject to the objection of plaintiff, to introduce his evidence on that matter. We think there was no abuse of discretion on the part of. the court in refusing leave to so amend the answer at that stage of the case. To have done so would have introduced a new and important element of defense not pleaded in the answer upon which the case went to trial, and a defense which the defendant must necessarily have known to exist, if it did exist, at the time he filed his answer; and no showing was made excusing the failure or neglect to so plead in the original answer, or that the amendatory facts were unknown to the defendant prior to the application. The statute, Sec. 4437, Comp. Stat. 1910, provides, “The party applying to amend during the trial shall be required to show that the amendatory facts were unknown to him prior to *456the application, unless in its discretion the court shall relieve him from so doing.” Aside from the statute the rule is quite uniform that it is not an abuse of discretion for the court to refuse to allow an amendment on the trial which materially changes the cause of action or defense. (Gale, Adm’r. v. Foss, 47 Mo. 276; Wixon v. Devine, 91 Cal. 477, 27 Pac. 777; Pierce v. Bruman, 88 Minn. 50, 92 .N. W. 507; Moyers v. Fogarty, 140 Ia. 701, 119 N. W. 159; Barrett v. Kansas & T. Coal Co., 70 Kan. 649, 79 Pac. 159; Phenix Ins. Co. v. Stocks et al., 149 III. 319, 36 N. E. 408; Deline v. Ins. Co., 70 Mich. 435, 38 N. W. 298.)
While the court refused to allow the defendant to amend his answer, he did permit him to introduce his evidence tending to prove fraud and misrepresentations on the part of the plaintiff as to the indebtedness of the company, and tending to prove that he was only to assume certain specified debts. But on those matters the evidence was conflicting and to our minds was insufficient to sustain the charge of fraud or misrepresentations had the amendment been allowed. At the close of the evidence the court, on motion of plaintiff, excluded all testimony offered by defendant attempting to alter or vary the terms of the written agreement. In this there was no error. Under the pleadings such testimony was clearly inadmissible. Many rulings of the court sustaining objections to testimony are assigned as error in the motion for a new trial, but as they related to the testimony offered to vary the terms of the writing need not be considered separately. It is also assigned as error that the court excluded the testimony of one Whitney, a witness for defendant. Counsel are mistaken in this. The record shows that but one question asked this witness was objected to by counsel for plaintiff and that objection was overruled, and at the end of his examination in chief counsel for plaintiff moved to strike out all of his testimony as incompetent, irrelevant and immaterial, which motion was denied. It is also made a ground in the motion for a new - trial, that defendant was surprised that this witness did not *457testify to certain matters which it is stated in the affidavit in support of the motion he had said he would testify to; but he was not interrogated as to those matters, and it cannot be assumed that he would not have so testified had.-he been examined as to them. A new trial is also urged for the reason that one Traphagen, a witness for defendant, and who had been summoned, did not appear at the trial on account of a death in his family. But no continuance of the case or postponement of the trial was asked for that reason and in those circumstances it was too late to complain after judgment. Another ground of, the motion for a new trial is alleged newly discovered evidence. This new evidence consists of the testimony of persons who were interested in the company before, at the time of, and subsequent to the transaction and what could be shown by the books of the company. Some of this evidence would be inadmissible under the pleadings and much of it merely cumulative. In preparing his case for trial it was the duty of defendant to make inquiry of those persons whom he knew would be most likely to know the facts necessary to establish his defense. It does not appear that these persons were consulted about the matter, or the books of the company examined before the trial, nor is any reason for the failure to do so stated, or that any effort was made to produce such evidence on the trial. A party cannot neglect to exercise such reasonable diligence in the preparation of his case as the circumstances would reasonably suggest and as will enable his attorneys to take the necessary steps to procure the evidence, go to trial without it, and when defeated be entitled to a new trial for the lack of evidence which could have been produced had proper diligence been exercised.
It is further contended that the court erred in permitting the plaintiff to introduce any evidence for the reason that the petition did not state facts sufficient to constitute a cause of action. With that contention we do not agree. The substance of the petition is set out at the beginning of *458this opinion and we think it' unnecessary to discuss that question more at length. We think the case was fairly tried upon the issues presented by the pleadings, and a correct judgment entered on the evidence.
Finding no prejudicial error in the record the judgment is affirmed. ' Affirmed.
Scott, C. J., and Potter, J., concur.