Where in an action for damages sounding in' tort the testimony of the plaintiff clearly and unmistakably establishes negligence on the part of the plaintiff, directly and proximately contributing to the production of the injury complained of, and there is m> evidence in the record tending to show that the negligence of the other party was wanton or wilful, and hence of such a character as to relieve against contributory negligence, it is the duty of the trial court, at the close of all the evidence, to direct a verdict in favor of the defendant and the omission so to do is prejudicial error.