In coming to this conclusion, we note that negligence, if any, by Mid-South in allowing the ramp to become slippery merely furnished a condition which reacted with the independent act of the spectator to cause Johnson's injury. As such, it was a remote cause and not a proximate cause of the injuries. See generally, Gaines, supra; Thompson v. Presbyterian Hospital, Inc., Okla., 652 P.2d 260, 264 (1982); Hunt v. Firestone Tire Rubber Co., Okla., 448 P.2d 1018, 1023 (1968); Pepsi-Cola Bottling Company of Tulsa v. Von Brady, Okla., 386 P.2d 993, 996-97 (1964); and City of Altus v. Wise, 193 Okla. 288, 143 P.2d 128, 131 (1943). Johnson's injury resulted from the unforeseeable act of the unknown patron, and under the facts stated, Mid-South did not violate any duty owed to Johnson, nor was there any showing that Johnson's injury was proximately caused by any negligent act of Mid-South.
We have repeatedly held that the defense of contributory negligence is a defense which must be plead and proved.Hunt v. Firestone Tire Rubber Co., 448 P.2d 1018, 1021 (Okla. 1968); Hair v. Wilson, 391 P.2d 789, 790 (Okla. 1964); Colonial Refining Co. v. Lathrop, 64 Okla. 47, 166 P. 747 (1917). The doctor counters, however, that at the conclusion of the evidence she requested that the court amend the pleadings to include the defense of contributory negligence which is permitted under 12 O.S. 1971 § 317[ 12-317].
We agree. In the case of Hunt v. Firestone Tire Rubber Co., Okla. (1968) 448 P.2d 1018, this Court in the syllabus stated: "2.
Southwestern Motor Carriers, Inc. et al. v. Nash, 195 Okla. 604, 159 P.2d 745. In Hunt v. Firestone Tire Rubber Co., Okla., 448 P.2d 1018, we stated: "The proximate cause of any injury must be the efficient cause which sets into motion the chain of circumstances leading to the injury; if the negligence complained of merely furnished a condition by which the injury was possible and a subsequent independent act caused the injury, the existence of such condition is not the proximate cause of the injury. * * *"
" Runyon v. Reid, 1973 OK 25, ¶ 37, 510 P.2d 943, 949. This rule is based on the underlying rule that "`if the negligence complained of merely furnished a condition by which the injury was possible and a subsequent independent act caused the injury, the existence of such condition is not the proximate cause of the injury.'" Id. at ¶ 34, 510 P.2d at 948 (quoting Hunt v. Firestone Tire Rubber Co., 1968 OK 184, 448 P.2d 1018). "However, if the intervening cause is foreseeable, then the chain of causation extending from the original act to the injury is not broken by the independent intervening agency, and the original wrongful act will be treated as the proximate cause of the injury." Id. at ¶ 35, 510 P.2d at 948.
In the second place, even if the plaintiff was guilty of negligence in going between the cars, it was for the jury to say whether the negligence of the defendant in moving the cars suddenly and violently without signal or warning was not the sole proximate cause of his injury * * * in view of the evidence as to the length of time that cars had been blocking the crossing and the custom of persons to cross between them in such circumstances. In Hunt v. Firestone Tire Rubber Co., 448 P.2d 1018 (Okla. 1968), the court explained that the analysis of proximate cause must be such as to establish it as the efficient cause which sets in motion the chain of circumstances leading to the injury; and if the negligence alleged merely furnishes a condition by which the injury was possible but a second independent act caused the injury, then the existence of the condition cannot be the proximate cause of the injury. We have recently ruled, in Sweenhart v. Co.-Con, Inc., 95 N.M. 773, 626 P.2d 310 (1981), that even though a prima facie showing of plaintiff's negligence has been made, summary judgment is improper if the issue of proximate cause remains.