In the present case the defendants’ general demurrer to the petition was overruled and no exception was taken to such judgment. While the petition was thereafter amended, the amendment did not materially change the cause of action so as to open the same to demurrer. Davidson v. Consolidated Quarries Corp., 99 Ga. App. 359 (14) (108 SE2d 495); Johnson v. Ellington, 196 Ga. 846 (4) (28 SE2d 114). Therefore such judgment established the law of the case and unless such judgment is reversed the plaintiff is entitled to a verdict if the allegations of the petition are proved. Wilder v. Harrison, 102 Ga. App. 446 (116 SE2d 516). When a court passes upon a motion for a nonsuit it decides only one question, that is, do the allegations and the proof correspond? If a plaintiff proves his case as laid, he is entitled to prevail against a nonsuit. Benton v. Owens, 105 Ga. App. 389 (124 SE2d 756). Since the plaintiff proved the material allega*348tions of its petition, the trial court did not err in disallowing the motion for nonsuit.

Judgment affirmed.