March 20, 1974. June 21, 1974. Trespass — Practice — Summary judgment — Plaintiff bitten by dog — Owner of dog having no reason to know the viciousness or dangerous propensity of dog — Rebuttal testimony — Refusal of court to allow witness who had testified in plaintiff's case-in-chief to testify in rebuttal — Failure of plaintiff to move to have case-in-chief reopened — Discretion of court — Credibility of witnesses. 1. In this case, the eleven-year-old plaintiff was attacked and bitten by defendant's