Plaintiff must plead the ultimate facts upon which he relies for a recovery else he can not prove them. Burnett v. Edling, 19 Tex. Civ. App. 711, 48 S. W. 775. To entitle him to recover commissions on a particular contract of employment he must plead it. Armstrong v. O'Brien, 83 Tex. 635, 19 S. W. 268.