much prefer to deal through an individual."
Under these facts, as Justice Gaines said, the principal being disclosed and the note showing that Stevenson, the agent, is bound, the bank "elected in the contract itself to look to the agent, and the principal is not liable." Heffron v. Pollard, 73 Tex. 96, 11 S.W. 165, 166. The basis for the rule was there stated to be that if plaintiffs knew when the contract was made that it was made for the benefit of a disclosed principal, "the writing showed that they had elected to look to the agent for its performance, and parol evidence was not admissible to vary the writing to show that they did not so elect." The rule is "very different from the case of an undisclosed principal", the Supreme Court there said. See Farrier v. Hopkins, 131 Tex. 75, 112 S.W.2d 182; First State Bank of Riesel v. Dyer, 151 Tex. 650, 653, 254 S.W.2d 92, 95; Garcia v. Yzaguirre, Tex.Com. App., 213 S.W. 236, 240; Day Ranch Co. v. Hubert & Woodward, Tex.Civ.App., 32 S.W.2d 252, writ ref.
In our opinion appellants' contention is correct also that judgment against Vector and Miltex was erroneous because the evidence is undisputed that the trust asserted by the bank was an express trust relating solely to realty. It was not a resulting or constructive trust. Under Art. 7425b-7, Vernon's Ann.Civ.Stat., parol evidence was not admissible to establish such an express trust. See Sevine v. Heissner, 148 Tex. 345, 224 S.W.2d 184; Morrison v. Farmer, 147 Tex. 122, 213 S.W.2d 813.
*539 The bank says the judgment is sustainable on its theories of ratification and estoppel. There are equitable defenses. Since they are defensive in character, they do not create liability or a cause of action. Their function is "to preserve rights, not to bring into being a cause of action." Southland Life Ins. Co. v. Vela, 147 Tex. 478, 217 S.W.2d 660, 663; Cotton Belt State Bank v. Roy H. Hatcheries, Tex. Civ.App., 351 S.W.2d 325. They do not constitute a cause of action or basis for one. Sessions v. Whitcomb, Tex.Civ.App., 329 S.