Where a sub-agent, employed by real estate agent under his general authority, was directed by the broker to continue his efforts, after the option which he had procured to be taken was cancelled, the principal was not liable for a commission on a sale by reason of the sub-agent's acts pursuant to the agent's directions. Sorenson v. Smith, 129 P. 757, 65 Or. 78, 51 L. E. A. (N. S. 612, Ann. Cas. 1915 A, 1127; Judg. aff. on real estate, 131 P. 1022, 65 Or. 78; McCombs v. Moss, 181 S. W. 907, 121 Ark. 533; Reasoner v. Yates, 134 N. W. 651, 90 Neb. 757.