Mr. Justice Clark delivered the opinion of the court.
2. Guaranty, § 3*—when officer of corporation not liable. An officer of a corporation refused to sign a form guarantying payment of the corporation’s order hut marked the order with the letters “O. K.,” and his clerk without authority wrote the seller in his name, the seller that the “O. K..” would have to suffice as a guaranty. The alleged guarantor testified the clerk had no authority to write such letter, that it was not written in accordance with the directions given and that he marked the order as an approval. Held, a guaranty was not established and a verdict should have been directed. 3. Guaranty, § 12*—scope of liability. The liability of a guarantor is limited to the express terms of his undertaking and cannot be extended by implication.