It is where there has been an integration whereby all prior and contemporaneous negotiations are superseded by the writing or writings that the parol evidence rule is applicable. ( Estate of Gaines, 15 Cal.2d 255 [ 100 P.2d 1055]; Code Civ. Proc., § 1856; Morgan v. Green, 86 Cal.App. 216 [ 260 P. 596]; Laughlin v. Haberfelde, 72 Cal.App.2d 780 [ 165 P.2d 544]; 4 Cal.Jur. 10-Yr. Supp. (1943 Rev.) 146, § 192; 6 Cal.Jur. p. 227, § 150; George Herz Co. v. Solt, 23 Cal.App.2d 178 [ 72 P.2d 251]; Witherow v. United American Ins. Co., 101 Cal.App. 334 [ 281 P. 668]; Wakefield v. Wakefield, 37 Cal.App.2d 648 [ 99 P.2d 1105]; Symonds v. Sherman, 219 Cal. 249 [ 26 P.2d 293].) [2] Defendant next contends the purchase price should be $7,500 instead of $8,000.

Respondent, in support of the findings and judgment of the trial court, urges that the instrument is testamentary in character and not effective because not executed with the formalities of a will; that there was no valid gift because decedent did not surrender dominion of the subject of the gift; that under the terms of the permit issued by the Commissioner of Corporations decedent could not lawfully make a gift; and that there could be no valid gift without compliance with section 330.1 of the Civil Code, which provides that title to a stock certificate and the shares represented thereby can be transferred only by indorsement or assignment and delivery of the certificate. The general rules with respect to the necessary elements of a gift causa mortis are well set forth in Wakefield v. Wakefield, 37 Cal.App.2d 648, 651, 652 [ 99 P.2d 1105], wherein appears the following: ". . .

The trial court has found on substantial evidence that there was adequate consideration for the contracts, that they were mutually advantageous, fair and equitable, and that they were entered into knowingly and voluntarily. Therefore, assuming that the legal relationship which existed between the parties plus the defendant's activity in procuring the execution of the contracts was sufficient to raise a presumption of actual confidence and made a prima facie case which cast upon defendant the burden of proving the absence of undue influence (see Johnson v. Clark, supra, at page 534; Jorgensen v. Dahlstrom, 53 Cal.App.2d 322, 333-334 [ 127 P.2d 551]), still we must recognize the fact that the presumption is a disputable one ( Wakefield v. Wakefield, 37 Cal.App.2d 648, 654 [ 99 P.2d 1105]) and that it was competent for the trial court on the evidence disclosed by the record herein to find that the presumption had been dispelled and the burden discharged. ( Nessen v. Nessen, 218 Cal. 59, 61 [ 21 P.2d 415]; Rocha v. Rocha, 197 Cal. 396, 407 [ 240 P. 1010]; Wilbur v. Wilbur, 197 Cal. 1, 15 [ 239 P. 332]; Best v. Paul, 101 Cal.App. 497, 499 [ 281 P. 1089].)

In other words, it is just as much the function of the trial court to resolve a conflict between opposing inferences as it is to resolve a conflict between contradictory statements of fact. ( Mah See v. North American Accident Insurance Co., 190 Cal. 421, 426 [ 213 P. 42, 26 A.L.R. 123]; MacDermot v. Hayes, 175 Cal. 95, 104 [ 170 P. 616]; Kelly v. Brown, 2 Cal. Unrep. 536, 537 [8 P. 38]; Bank of America v. Perry, 41 Cal.App.2d 133, 136 [ 106 P.2d 53]; Wakefield v. Wakefield, 37 Cal.App.2d 648, 655 [ 99 P.2d 1105]; Los Angeles City High School Dist. v. Kennard, 94 Cal.App. 450, 452 [ 271 P. 342].) Nor has appellant avoided the force of this rule by pointing out certain alleged improbabilities in the testimony of respondent concerning the transactions herein involved, and arguing therefrom that the trial court should have found that the respondent was paid in full for his services rendered on the ranch.

[5] The construction of an ambiguous contract is first presented to the trial judge, whose determination "will not be disturbed on appeal unless it be unreasonable and unjustified." ( Dreyer v. Cole, 210 Cal. 339 [ 292 P. 123]; Wakefield v. Wakefield, 37 Cal.App.2d 648, 654 [ 99 P.2d 1105].) But in view of the fact that some other evidence aside from the lease was received at the trial, and that it is not contrary to the construction placed upon the lease, all reasonable inferences must be indulged in support of the finding.

In two of them there was actual delivery. Arizona Title Guarantee Trust Co. v. Wagner, 75 Ariz. 82, 88, 251 P.2d 897, 903 (1952); Wakefield v. Wakefield, 37 Cal.App.2d 648, 653-55, 99 P.2d 1105, 1108 (1940). In another there was constructive delivery.

On the contrary, it is stipulated that Cecil retained the only key to the box and that the money found therein upon his death was placed there by him. Again the attempted gift failed for want of delivery. Hynes v. White, 47 Cal.App. 549, 190 P. 836; Wakefield v. Wakefield, 37 Cal.App.2d 648, 99 P.2d 1105; Hausfelder v. Security-First Nat. Bank, Cal.App., 176 P.2d 84; Hartt v. Brimmer, Wyo., 287 P.2d 638; Jackman v. Jackman, 271 Mich. 585, 260 N.W. 769; Reeves v. Lyon, 224 Iowa 659, 277 N.W. 749; Lowry v. Florida Nat. Bank of Jacksonville, Fla., 42 So.2d 368; Annotation 14 A.L.R.2d 948. The joint tenancy entered into by the plaintiff and the deceased with the Downey State Bank, among other things, provides:

The burden is on the alleged donee to rebut this presumption and to establish that the claimed gift was fairly and properly made to him. Gilmore v. Lee, 237 Ill. 402, 86 N.E. 568, 127 A.S.R. 330; Wakefield v. Wakefield, 37 Cal.App.2d 648, 99 P.2d 1105; Baber v. Caples, 71 Or. 212, 138 P. 472, Ann. Cas. 1916C, 1025; In re Moyer's Estate, 341 Pa. 402, 19 A.2d 467; McBride v. Mercantile-Commerce Bank Trust Co., 330 Mo. 259, 48 S.W.2d 922. And see Leo N. Levi Memorial Hospital Assn. v. Caruth, Admr., 213 Ark. 1, 208 S.W.2d 983. Plaintiffs attacked the alleged gift in the principal case on two grounds: (1) that no gift was in fact ever made by Charles Eibler to Lawren Baker, and that Baker was merely keeping the money for the brothers, and (2) that if a purported gift was made Charles lacked the mental capacity to make it effectually. The obligation to produce convincing evidence was on the defendants on these issues.