McCLELLAN, J.

Detinue for three head of cattle, instituted by appellant against Nellie Freeman, for whom Pelham Sitz & Co. were substituted as defendants. Code, § 6051. There was judgment, on verdict, for the substituted defendants.

No question having been raised in the' trial court as to the propriety of the substitution for the original party defendant, the first assignment of error is without merit.

The plaintiff claimed under a mortgage of date January 31, 1921, and the substituted defendants claimed as assignees of a mortgage of date February 28, 1918. The assignment, of this mortgage to the subs(;i *265 tuted defendants purports to have been made November 10, 1921. The plaintiff contended that this mortgage had been paid and discharged by the appropriation and salé, by substituted defendants, of two mules, described therein. The court instructed the jury, in accordance with theories proposed in the evidence, that, if the substituted defendants sold the mules after they acquired this mortgage, then the mortgage was paid and discharged; whereas, if the appropriation and sale of the mules was effected before they became assignees of this mortgage, the mortgage was not paid. There was no fault in the instruction mentioned. The familiar rules for the application of payments, which the brief for appellant would invoke, do not apply to strangers to the contracts or obligations involved. So far as the mortgage of February, 1918, was concerned,, unless Sitz & Oo. had become assignees of that mortgage before the sale of the mules they could not apply the proceeds to an indebtedness then held by another. The ques> tion contested is one of asserted payment of the debt secured by the mortgage of February, 1918.

Under the, evidence, the plaintiff was not entitled to the general affirmative charge requested.

Affirmed.

ANDERSON, O. J., and SOMERVILLE and THOMAS, JJ., concur.