Under an agreement to pay commissions for negotiating a "satisfactory lease," the lessor can not arbitrarily refuse to accept a lease negotiated and thereby defeat a claim for commissions. Mullaly v. Greenwood, 127 Mo. 138, 29 S. W. 1001; Casaner v. Johnson, 122 N. E. 444, - Mass. Sup. - . See also Secs. 374, 454.