after stating the case: As a general rule, one who subscribes his name to a written contract at the place usual for obligors in such a paper is bound by its terms as a written agreement, though his name may not so appear in the body of the instrument (9 Cyc., p. 301), the test being, whether on perusal of the entire instrument and without the aid of extrinsic evidence it plainly appears that such signer intended to execute it and be bound by its terms. Clark v. Rawson, 2 N. Y., 135 (Denio, vol. 2); Perkins v. Goodman, 21 (Bar.) N. Y., 218; Ex parte Fulton, 7 Cowen (N. Y.), 484; Thompson v. Coffman, 15 Oregon, 631; Staples v. Wheeler, 38 Me., 372; Danker v. Atwood, 119 Mass., 146; Amer. Digest (Cent. Ed.), Contracts, sec. 773.
By reason of the test suggested, the principle will to a great extent, but not universally, be confined in its application to contracts which create a present obligation and are on their face unilateral in operation, as in the case of a promissory note, and is not permissible where the written instrument contains mutual or dependent stipulations, so that without the aid of extrinsic evidence it cannot be determined whether a third person who joins in subscribing to the paper intended to come under obligation to one or the other of the contracting parties. An instance of this occurring in Blackwell v. Davis, 128 Mass., 538. It is also held with us, and by the weight of authority elsewhere, that the general rule does not obtain in instruments *446conveying or assigning rights and interests in realty, more particularly when the rights of married women are claimed or assailed under deeds purporting to be made by the husband and in which the wife’s name only appears with him as subscriber to the instrument. In such case the decisions are that to bind the wife or convey or affect her interests there must be apt and operative words of assignment by her in the body of the deed. See King v. Rhew, 108 N. C., 696; Harrison v. Simans, 55 Ala., 516; Bruce v. Wood, 42 Mass., 542; Lancaster v. Roberts, 144 Ill., 213.
In the case before us, while the contract purports to assign an existent interest, in the absence of some contrary stipulation in the policy of insurance, the right to make such assignment rests with the beneficiary, George Briley (Bliss on Life Insurance, 2 Ed., sec. 337), and on a perusal of the entire'instrument it plainly appears that it was his intent to transfer the policy to the assignee. He could have had no other reasonable purpose, and under the general principle first stated the judge correctly ruled that the paper-writing was the written contract of said beneficiary and amounted in form to an absolute assignment of the same.
While we uphold his Honor’s decision in the respect suggested, we are of opinion that he erred in charging the jury that the defendant was required to establish his position on the second issue “by clear and convincing evidence,” such position being that the policy, though taken under an assignment absolute in form, was in fact held as collateral. This wholesome rule as to the degree of proof has been frequently held to apply in this State, and in proper case obtains both as to real and personal contracts (Salinger v. Perry, 130 N. C., 134) ; but in the case before us, and others of like import, it only prevails where it is sought to alter or reform a written instrument or annex a trust thereto because it is necessary to do so in order to assert the right claimed or to avoid a material contradiction of a written contract or the portion of it which the j)arties have reduced to writing. Thus, when it is alleged that a deed conveying realty, absolute in form, was intended as a mortgage, contracts concerning realty are required to be in writing, and *447in order to carry out the contract as claimed, it is necessary to reform a solemn written instrument, and the principle referred to applies; and where, as in the case of Salinger v. Perry, supra, the position contended for involves a direct contradiction of the written contract, this too necessitates a change in the written instrument, and must be established by the same degree of proof. The recent cases of Fertilizer Co. v. McLawhorn, 158 N. C., 274; Walker v. Venters, 147 N. C., 388; White v. Carroll, 147 N. C., 330, are instances of this character; but in these assignments of ordinary mercantile or business contracts it is very generally held that it is competent for the parties to prove by parol that as a part of the agreement the instrument should be held as collateral to secure a debt. Such a position does not necessarily require or involve a change in the writing, but recognizing the contract as written and as necessary to pass the title, it only superadds the additional stipulation indicated which the parties have made by parol. It presents a case where part of the contract only is in writing, and the additional feature having been made by parol and being valid when so made, can be shown and established by a preponderance of the proof. The principle was discussed in two cases at the present term, Pierce v. Cobb, ante, 300, and Lytton v. Lumber Co., and is illustrated in several recent decisions of the Court. (Typewriter Co. v. Hardware Co., 143 N. C., 97; Evans v. Freeman, 142 N. C., 61), and, as stated, is very generally applied in assignments of these ordinary mercantile contracts taken as collateral to secure indebtedness, including insurance policies, certificates of stock, etc. Kendal v. Insurance Co., 171 Mass., 568; Riley v. Bank, 164 Mass., 482; Westbury v. Summers, 57 S. C., 467; Chamberlain v. Butler, 61 Neb., 730, reported 87 Am. St. Rep. and principle referred to in editorial note at p. 511; Brick v. Brick, 98 U. S., 514.
"We are not inadvertent to the statement in the record, at the top of the written contract, ‘purporting to describe the same as “an absolute assignment and power of attorney.” It was not shown that such a heading was or was not intended to be a constituent part of the contract, and for aught that appears it may be only an estimate of plaintiff as to its contents, and cer*448tainly on the facts presented it should not be allowed substantial effect in the interpretation. Milhusen v. Eardman, 103 N. C., 27; Summers v. Hibbard, 153 Ill., 102; 2 Page on Contracts, sec. 600.
For the error indicated defendant is entitled to a new trial of the cause, and it is so ordered.